What's the most alarming experience you've had with a stranger?

I was sitting in my car in the parking lot of the beer store, playing a game on my phone, procrastinating on my mission to buy beer.
I had locked the door from pure paranoia (I'm just a paranoid guy).
A guy on the sidewalk stepped onto the parking lot and walked toward my car. I thought little of it, but I noticed. He got closer and closer, and then he grabbed the handle and tried to open the driver-side door.
It was locked so he casually kept walking like everything was normal.
It was broad daylight. I still have no idea what he would have done if the door had been unlocked. But I was sitting and in the more vulnerable position.
- I had a similar experience. I was maybe 17, driving alone at night to choir practice. Stopped at a red light on an empty street and a guy walked straight up to my car and tried to open the passenger door. It was locked and thankfully the light turned green a second later. I peeled out.
  Human beings are FUCKED.
  
  All these stories make me feel good about my habit of locking the car doors the second I sit down in the driver's seat.
- But I was sitting and in the more vulnerable position.
  His crotch would've been very much within punching reach though

When my brother and I were pretty young, my dad once left us in the car to run in fast and grab something from a grocery store. (I know, bad, but this was several decades ago. It was more normal back then.)
While he was gone, an older man came up to our car and started aggressively trying to unlock the door.
My brother and I froze in fear and just watched as he kept trying to unlock the door. We had unbuckled ourselves to play while my dad was inside, so we were on the floor.
We both just shrunk down into the floor and hid silently, not knowing what to do.
After probably 30 seconds, he put his hands up over his eyes and looked in the car window, then made a frustrated sound and quickly left.
Once our dad came back a few minutes later, my brother and I told him what happened. We were pretty freaked out.
He said the man was probably just confused because he was elderly and thought it was his car. I think that makes sense, but as little kids alone, it was still really scary.
- my dad once left us in the car to run in fast and grab something from a grocery store. (I know, bad
  Is this bad? Where? My parents often left us in the car, it's totally normal here in Denmark.
  
  I'm in the US and we lived in a medium-sized city at the time, so a higher level of danger than in many other developed countries.
  
  The main thing I'd be concerned about is if it's hot. I always wait in a car if someone is going into a shop or something like that as I'm lazy as fuck and can't be arsed walking around.
  
  Could also be very hot in the car in some places

A stranger trying to grab me by the back of my neck as I rode past on my bicycle. He got ahold of my hoodie but didn't have a good grip. I got away and pedalled like hell.

While I was working downtown one summer, I stopped off in a CVS in the center of the main part of the city to buy some water.
On my way into the store I walked past a homeless black man. He had on a thigh-length coat with a hoodie under it, jeans, and boots that were half laced. The cornea of one eye was milky, presumably damaged at some point and probably blind or nearly so.
I grabbed my water and went to the back of the line, a few feet from that homeless guy. He got a look at me and said with a giant smile "Hi Death_Equity!" like greeting an old friend. I said "Hey man." hiding how surprised I was and he walked away. I was too caught off guard to find out who he was, I was reeling that he knew my name. I have no idea who he was, but he somehow knew my name. I didn't have a name tag on, nobody else was in the store with me that could have said my name, I didn't have a credit card out that he could have read. He either was a voodoo priest who gave his eye for sight beyond sight, or he is someone who knew me and I did not know or recognize him.
When I got back to the truck, I told my coworker about it and was fairly freaked out about this random half-blind homeless guy that knew me by name.
I have spent hours since trying to figure out who that man was to me. I feel horrible knowing that he must have been someone I knew and have forgotten about him as society has. Maybe I went to school with him as a kid? Maybe I met him through work before he was homeless? I wish I knew, but he surprised the fuck out of me.
- I understand being too freaked out to ask how he knew you, plus probably not wanting the interaction and having to get back to work, but like... damn. I know I'd have asked, I'd be too curious not to and I'd feel bad for blanking him if we did know each other. My partner hates that I engage with randoms like that though, so maybe I'm too blase about it?

I was sitting in my pickup outside my apartment listening to the radio and some guy just...got in. I asked "can I help you?" and the look on his face when he realized his mistake was priceless. In his defense Lyft had just started in my area and there was only one other vehicle that looked like mine in that part of the city.
- Something similar happened to me and my brother maybe 15 to 20 years ago. Our parents were in the shop and we were sat in the car waiting but the car had tinted windows in the back. Some guy gets into the car not realizing that there was anybody in it and when he does he apologizes and says that he mistook our parents car for his own as they were the same make/model or something.
  
  I've done that. Even though to myself "who put this apple here?" as I sat down in the passenger seat.
- I have done that too thought it was my mothers car which came to take me home I opened the trunk put my bags in closed it walk all the way around hop in to realize there wasn't my mother at the wheel ... That dude face ... Priceless ... Mine probably too... Apologized took the bags and went hearing my mother laughing for the rest of the trip se was parked right in front she saw everything...

- I don’t know the whole situation but reading this it could be he just happened to go the same way and maybe whistled because he wanted to make himself noticed by animals. But it sure seems creepy!

A patient came into the ER for chest pain. He was uncomfortable and a bit anxious but otherwise normal. The guy was a military officer and very athletic. I go in to draw his blood and get some background information, we're chatting as I get my supplies ready, and as I'm putting the needle in his arm he says "you're from the government." in a very cold voice. I look up and his face has completely changed. He's furious and looks like a cornered animal. Before I can ask "what?", he screams it again and rips the needle out of his arm. He kicked me backward and then stood up while screaming "you're from the government" repeatedly. I get to my feet and he charges, easily twice my size and probably trained to kill. I run to the far end of the ward, he keeps running after me, and the only thing that saved me was having my paramedic boots on. I managed to get one good kick with the steel toe into his shin and brought him down after which I got him into a restraint position and the doc sedated him. I had never seen psychosis suddenly come on like that from a completely neurotypical presentation. A switch flipped mid-conversation and he was determined to kill me without any ability to perceive pain or limit the strength of his muscles. I broke his leg and he was unaffected, still trying to get up and attack me again.
- Pretty much. What got me is that he was an aviation officer with a pretty high rank. They have extremely strict entry requirements, regular psychological screenings, constant checks by flight surgeons. He was around 20 years beyond when a lot of psychiatric illnesses start presenting and as far as I know we never established an etiology for it. The only trigger I could ever think of was the needle piercing him but until that moment he showed absolutely no anxiety about the blood draw and I thoroughly explained why we were drawing two separate chest panels over the next few hours. One moment he fully understood what was happening and was discussing it, the next it was chaos. After really fine-tuning my sense of shit about to kick off from that line of work, I had zero indication anything was off about the situation.

I was out in the garden when a dude waked by. One of us waved, I don’t remember which, and the other waved back, sort of neighborly one hand up for a second wave. By the time he crosses the bush, he has turned back to cross my (luckily fairly large) yard, walking towards me. I run inside, and lock the door and yell at my SO to come downstairs there was a scary man at the door. SO confronts the man while I hide. Dude makes up a story about how someone yelled at him from our balcony, and he thought it was his friend. SO says he doesn’t believe him, and he better not show his face around here again if he wants to make it home alive.
- Someone was walking towards you so you ran?
  
  Sometimes there's just something that seems wrong. Why did the man turn back? Why did he then claim someone had called out to him? The OP felt something was off and acted on it.
  
  Different places right? Where I live you're as like to get shot as not for approaching someone's house on foot at night without announcing who you are and why you're there.
  Someone came stealthily up to our gate late at night once when my partner was alone in the side yard. Dog ran him off when he tried to open the gate, but I don't like to think what might have happened if he wasn't out with her. There is literally zero chance he was there for any legitimate reason and she was clearly visible in a light at the back of the property.

Probably being run off the road and attacked with a knife because I wouldn't/couldn't get out of the way of some methed out asshole.
My old car had a gas shut-off if enough big bumps happened.
I was doing 5 over the limit and a dude comes up behind me, honking and going batshit.
The road was a curvy country road with no real way to pull off safely. Too curvy to put my ass on the line speeding up more. So I just waved him around and slowed slightly on a slightly less curved section.
Dude revs up, then starts to jerk into the side of my car.
I brake hard and steer as best as possible to what little shoulder exists.
Passenger side is barely hanging on the edge of a five foot drop, and of course the bump slipping off the paved section hard set off the gas shutoff.
Fine, whatever. The switch to cut it back on is in the fucking rear hatch area.
So I drag my sasquatch ass out out the car to go hit it.
Dude comes screeching back from the other direction. Brakes hard, practically jumps out of the car, pulls a shitty switchblade and comes at me.
Shit went down. I have one small scar, he was worse off. I used to tell the whole story, but people are fucking idiots, and I'm too old for internet bullshit.
- Shoot, share it anyway. That's what it's all about, people just sharing themselves and maybe getting a chance to walk that mile in the other person's shoes :)
- SHoUlDn'T hAvE bEeN rIdInG iN tHe LeFt LaNe

I was on a hiking trail ... I could see at least 50 meters/yards back.
I stopped and took a couple pictures of some deer super close to the trail. Looked back, then kept walking... Nobody there.
A matter of moments later, I hear footsteps behind me. I had headphones on but I wasn't playing my music very loud. I take a quick glance back, the guy is wearing a grey T-shirt, a blue ball cap, blue jeans, and white sneakers. Literally the most generic outfit you can possibly have and he's looking at the ground so I can't see his face.
I decided to call my friend who's always home on my phone. He picks up and I just start some BS conversation. Probably 15 seconds later, the dude vanished just as quickly as he'd come.
I don't know if he was just a really fast walker and my situational awareness was way off that day, but it did freak me out.

I’m guessing the nurse community probably has some outlandish stories to tell here.
- Not a nurse but a paramedic. Does getting a gun pulled on me by a crackhead count?
  Or a guy furiously masturbating in the back of my ambulance?

I can’t read this thread. I have a few scraps left of faith in humanity I’d like to retain.

- Is 2 hours later another time? I could use some crackhead lore building.

Getting mugged/pickpocketed and having my phone stolen - I was in a foreign country, didn't speak the language well and lost a lot of precious pictures that I didn't have time to backup (Google was being a fucking bitch and prioritizing storing some long videos I'd tried to mark as excluded from backup). It felt violating, especially for how cheap my phone was.

A guy in a rugby jersey, with the build of a rugby player, grabbed me by the shoulders and shouted in my face "I don't care if I die tonight!" And headbutted me right in the forehead After I told him I didn't have a cigarette. Luckily I was with 6 friends, they took care of it.
- Crazy that you needed six friends just to give him a cigarette.
  
  It was their last one. Convincing was needed

A guy followed me around the grocery store when I was around 20. I didn't have a car and didn't want to walk home with a stranger following me, so I just walked around the store for ages.
At one point some guy asked me if I noticed anything strange about the guy following me. I don't remember what I said. At another point, a friendly stranger started making small talk with me, and asked my name. I was nervous but that's really common around here and I didn't know how to leave the conversation.
I saw both guys reporting back to the guy following me.
Don't know what they wanted. I ended up hiding in the women's restroom for a few hours.
- They might gave been loss prevention. This is pretty common to see around here at places like Walmart.
  
  Unfortunately not. I left out some stuff because it's an unpleasant memory but on my walk there I saw him driving, and he pulled over to beat a dog in the backseat. Animal cruelty isn't really prosecuted here so it's weird he'd be that bothered by a witness.
  I was nervous and keeping an eye on him after that and sometimes I wonder if he thought I was up to something and got his buddies on the defensive. Or maybe he was a garden-variety creep and saw a fem-presenting person walking alone.

This might pale in comparison with all the other replies here, but one incident really made me uneasy.
I was seated inside a train minding my own business. I was wearing a loose shirt and an even looser pair of walking shorts. The shorts were made of thin and glossy material. It wasn't thin enough to expose my underwear but it readily shows any bumps or whatnot.
The train wasn't that full, and there were lots of empty seats. The train had longitudinal seating (two rows of seats facing each other, with some standing space in between. There's also an area where the train can "bend". This area has no seats of course. I was seated next to this "bendy area".
I remember having difficulty staying awake and was seated in an increasingly loose way. I caught a glimpse of a guy standing in front of me. He was leaning against the train walls and was on his phone.
Now, the train isn't the most quiet, but I distinctly heard an unmistakeable camera sound which jolted me awake. Selfie cameras on phones wasn't yet a thing back then and the way his phone is oriented, I can see the phone's camera lens pointed at me. The guy, noticing that I noticed the sound, quickly put the phone back in his pocket.
I might be wrong, I hope I was wrong, but I thought a stranger took a photo of me just a meter or two away from me.
That's it. Kinda underwhelming, I suppose but I was kept wondering why that guy, if it's indeed the case, took a picture of me.

I used to live in Bogota, Colombia for a couple years. The part of the city I lived in apparently just emptied on New Year’s Eve. It was eerie. The only people around were the various sketchy types.
Well, my friends and I stayed in, tripping on acid. We were just lying around, sitting on the stoop smoking, etc. One of my friends got some coke, went to meet up with a friend and go out.
Well, a couple hours after midnight, maybe 1:30 or so, I get a call from said friend. Now, he was on coke and we were on acid, so the vibes between us were way off. I’m not sure if anyone has ever taken acid and hung out or talked to anyone on coke, but I DO NOT recommend it.
Anyway, he calls in a panic because he’s at the bar up the street, he didn’t speak Spanish very well (and I, my friend and the two Colombian women we were with obviously did), so he called saying some guys weren’t letting him leave the bar, telling him they’d kill him when he came downstairs.
He said the bartender even told him he could stay at the bar overnight. Weird. But, he was on coke and didn’t speak the language, so entirely possible it was a huge misunderstanding.
Anyway, the four of us get this call and talk amongst ourselves about how we really didn’t want to get up, but we kinda had to. So we’re walking the few blocks, the four of us and a dog (she was an excellent dog, Kira. She was beautiful and chill but was protective of us when need be.)
We’re kinda strolling, tripping, laughing as we head toward the bar. A cab stops next to us, asking if we want a ride. We stand there for a second, debating whether or not that would make us safer in case we walked into something dangerous…but really didn’t factor in that there were four of us and a dog and we were going to pick up a fifth person. The cabbie was cool as we all, giggly and stupid, laughed liked maniacs trying to squeeze in.
We explain where we’re going, that we’re trying to pick up another person. Whatever, the guy was cool enough, so off we go around the block. As we pull up, a group of people is walking away. One of the people I’m with knew them, they say hi, and we pull up to an otherwise empty street.
After that group of people walks away, this street is deserted. So we get out, assuming everything is good. We ask the cabbie to pull over a little ways away and we might take a ride back. Well, as soon as he pulls off to park, this insane guy comes running up from behind us, shouting in our faces. Making a lot of noise, gesticulating wildly, generally pulling all of our attention to him.
Kira is barking like crazy, she’s pulling at the end of her leash, my friend holding her back as she clearly sees this dude as a threat. My friend holding her just looks at me like, “what are we doing here? This guy is nuts” with a sort of dismissive expression.
But then I see his eyes look past me, so I turn around, and see another guy on the other side of the street. And another two guys coming up the other street. We’re getting surrounded. Where these guys came from I have no clue. They were just like coming o it of the shadows.
And then there’s this super off-putting, really quiet, just…plain evil looking guy that suddenly slides up from behind us. It felt like he just fuckin apparated next to us. Dude made my blood run cold. No joke. I’ve never gotten such a bad feeling from someone before. I really can’t express to you his vibe. In this weird crew, he just seemed like…the killer. There’s no other way to describe it. He just had that aura about him.
That’s when I realized the first guy was serving as a distraction while we got cornered.
We start edging around these guys to the middle of the street, trying to keep them from backing us into the corner we were initially standing by. They keep trying to get in our way, but they couldn’t get too close because, thank god, Kira was going fuckin nuts. I genuinely think she saved our lives, because she was creating a barrier around us that no one could really get past without getting chomped. But, weirdly, neither of these two that were right in our faces even paid her any mind whatsoever. They avoided her, but they never looked down, they just kept looking straight at us.
So I start waving wildly to the cabbie, who is sitting half a block away, watching all of this. I’m making eye contact with him as he surveys the situation from the safety of his car. There are like six of these guys. All converging on us. And he was definitely considering driving away. I’m actually surprised he didn’t. In bogota, there’s not really any feeling of any stranger ever having your back. I truly felt, in all of the multiple scrapes I got myself in, that I was on my own. Even a few of my own friends stepped back and refused to risk their safety when a different dude tried to stab me (story for another time).
After a few moments too long for my liking, he finally makes a move to come pick us up. The one guy is still screaming at us, the silent guy is still just fuckin staring silently with those fuckin Manson lamps, and the rest are just encroaching more and more from every direction.
We fuckin slip back into the car, get away for a second, this cabbie drives us around the block once, and I call my friend to be at the bottom of the stairs when we circled back around. We pile him in on top of us and just…escaped with our fuckin lives.
It was the most bizarre situation that I ever truly felt like I was in serious trouble. It could’ve gone so wrong if Kira and this cabbie behaved any differently.
Oh, and when we got my friend in the cab? It was that initial group of acquaintances that was apparently doing the threatening. Not the seriously dangerous crew we tangled with. So who knows if it was even true in the first place.

Question, if I answer being kidnapped for half a week in a guestroom, does that make them still a stranger?
Possibly ambiguous answers aside, I'd have to say it's a long story that concerns what crazy things people do at a ward.

I was walking home as a young university student from the karaoke bar, not drunk or anything, and I had to climb a small hill which took about 15-20 minutes. This car was idling at the top and sat there the entire time I was walking. I became utterly certain the man in it was waiting to kill me and I became terrified. I reached the top of the hill, and indeed he was waiting for me "to offer me a ride home", but I think he decided looking at the terror stricken look on my face that I would be a bad victim. I'm pretty sure I narrowly missed getting abducted or something and if I had run or done anything different he'd have tracked me down.

Someone tried to mug me when I was walking back to my dorm room.

I was once stopped at a red light waiting to turn right. I glanced left, saw it clear, and started moving forward…but a tattered, sunburnt dude in a wheelchair had appeared out of nowhere and tried to cross in front of me.
I stopped in time, didn’t hit him, but must’ve scared him (or something), ‘cause he lost his fucking mind and started shrieking bloody murder, backed up a bit and started CLAWING at the passenger side window — not trying to open the door, just clawing, freaking my friend the fuck out — and screamed (exact quote), “I’LL KILL YOU, YOU MISERABLE BASTARD!!!”

I was jogging in the city and as I come out of this underpass a totally nude man crosses the grass and the path in front of me all while looking at me.
He wasn't scary or anything. It felt like he was just doing his thing.