What is a sexual fantasy you find hot but don't want to experience?

Threesomes. Sounds really hot, but I think it would mess with my very awesome relationship.
- It has been my fantasy forever. I've been married for over a decade now, and we both promised we would do this someday while we were dating. She has always had an interest in being with another woman, so it works out perfectly. It just can't be someone we know. Finally, a month ago, for her birthday we took the first steps, and I took her to her first strip club, and we both had a lot of fun. It was super fun seeing her not know what to do, be super shy, embarrassed, but clearly turned on and loving it! We talked about it some more the next day and think we're ready to see if we can make this happen someday. Honestly, my biggest fear at this point has nothing to do with myself or her falling for someone else, but how I have no idea how I expect to last long enough for it to be worth it!
- Threesome with 2 people I like, it would mess with my relationship and my head if I was in love with one of them
- Yup same
  
  Damn. It sounded like we had the right number of people on board...

Affairs. Great in porn, but I'd imagine it would be completely destructive to my personal life. So never.
- Second this. Never plan to dally.

Public sex 🫣
- Because of stage fright?
  
  Sex in the woods is great. Finding yourself on a sex offender registry because someone was walking their dog that day.. potentially life ruining.

Non-con stuff. Either end of it.
Like I know about cnc but I'm not sure if I'd actually want to partake in that cause I'm not 100% sure where the line is for myself even
- I love CNC, but you definitely need to know where the line is, for both yourself and your partner.
  It does force you to become better at understanding consent and communicating limits, so that's a nice upside.
- yeah same, i was thinking about it the other night, but i was like... even if i found someone into it, i don't know that i'd be okay afterwards
- What's cnc? Or do I not want to know?
  
  It's doing non-consensual things (e.g., rape) that a person has consented to before the fact. Different people do it different ways, there's usually some kind of safeword, and it typically involves 'forced' bondage and sexual acts. Like, I was dating someone for a while that wanted to be abducted off the street, strangled, tied up, and forcibly sodomized. That was their fantasy; they didn't want to know when it was going to happen, but they consented to it--and said they were consenting to whatever happened during it--beforehand. (It did not happen due to logistics; that's a very, very high risk scenario, since at least part of it plays out in public.) This person wanted to be used and abused by me for my own sexual gratification. They was much more of a masochist than I am a sadist.
  CNC gets risky in other ways, because it's easy to blow right past limits without realizing it, and get into sexual assault territory; part of the 'game' is that it's 'non-consensual', so it might be difficult to know when it's become non-consensually non-consensual.
  
  Concent non concent you concent to non concent type play

Even though I'm hetero, have always thought about a threesome with my wife and the other guy sucking my cock
- I'd be okay with fucking a female with a dick. Manly body doesn't excite me, but a dick doesn't drive me off. I'd prefer not the be one who is fucked tho.

It's kind of strange that people have sexual desires that they don't want to act upon. How does that happen?
- Sometimes the potential consequences of doing something irl are just... not worth it.
  For instance, risky public sex
  Fantasy: ooh the thrill of being caught, what'll happen? Such adrenaline, such stakes 😈
  Reality: Go to jail for indecent exposure, do not pass go, lose your job and be branded a sex offender in a government registry ☹️
- Religion?
  Social expectations?
  
  Not that I've seen in the comments yet I mean.
- It's called "post nut clarity" Sounds great thinking about it, but if you did it as soon as you finished cumming you would regret it.

There are plenty of things I can't do anymore, but I was shocked at how hot it was to do some of the things I thought I wouldn't like in real life.
I think masochism is the line where it's the most different - I like some pain IRL but it can quickly cross to where it's unsexy or only hot because I am doing it for the sadist, like as a submissive thing it's satisfying but the literal pain is just painful beyond what is gonna make the high or the arousal. In fantasy, where obviously I'm not hurting, that line is farther away, though it still exists.
You do need good communication and an enthusiastic partner to do any sort of threesome, I think it's fun (MFM), was better in real life than I'd imagined it would be.
CNC I have written about here, that is different in real life but not worse. I think because in your mind the other person is undefined, right? More like stuff being done to you. But in real life it's a real person with their own desires, they are driving, you are on their ride.

Watching a stranger bang my partner. Maybe multiple people or in a threesome situation. I wouldn't say I'm a cuck. I think it's just the idea of seeing my partner looking like an absolutely depraved slut that gets me going and a bit of a cum fetish.
In reality I would be worried about getting jealous or them getting too into it just for me to realize later that it isn't for me.