What irritates you the most with your own language?
Mine is people who separate words when they write. I'm Norwegian, and we can string together words indefinetly to make a new word. The never ending word may not make any sense, but it is gramatically correct
Still, people write words the wrong way by separating them.
Examples:
"Ananas ringer" means "the pineapple is calling" when written the wrong way. The correct way is "ananasringer" and it means "pineapple rings" (from a tin).
"Prinsesse pult i vinkel" means "a princess fucked at an angle". The correct way to write it is "prinsessepult i vinkel", and it means "an angeled princess desk" (a desk for children, obviously)
"Koke bøker" means "to cook books". The correct way is "kokebøker" and means "cookbooks"
I've known the difference ever since I decided to look it up one day, but I've always felt the 'in-' prefix was the wrong choice (especially when labeling potentially dangerous substances). "In-" is more often used to qualify a word as "not".
Problem: ambiguity of date terms like saying "this Wednesday" on a Thursday. Is the speaker referring to yesterday or the coming Wednesday six days from now? Not always clear.
Solution: I propose standardising our understanding of the week as beginning Monday, ending Sunday. At any point in the current week, "this whateverday" refers to that day in the current week, no matter if it's past or future. "Next whateverday" refers to that day in the upcoming Monday through Sunday week.
"This Wednesday", on a Thursday, is referring to yesterday.
"Next Wednesday", on a Thursday, is referring to a day six days from now.
(I also suggest adopting ISO 8601, writing dates in year-month-day order to avoid that ugly ambiguity.)