Tl;wr In my fifth year at school, at a gymnasium in Germany, I got a guy expelled from school by not speaking up, because I was to scared of the consequences.
He was one of those guys you have in your group, everyone kinda likes him, but no ones really a friend with him. We knew each other pretty well, sat together sometimes and played fußball together a fair bit.
Well we had art together, boring as hell class, teacher made us memorize the last names of the most important artists in history and as usual for boys in art class we did a whole lot of things we shouldn't have.
For some reason a sackzwicker was a thing back then, not sure what it's in English, comes close to the thing where you pull underpants up? Well this guy thought he would be cool and tried to do it to me, while sitting next to me.
A little bit more backstory, this was a pretty prestigious and stuck up gymnasium in a pretty stuck up area and all the teachers treated us like special snowflakes. Also fifth grade is the first year in the equivalent to highschool.
Alright, so he tried to perform the sackzwicker maneuver on me, sitting next to him, however he somehow missed the side of my undies and grabbed my ballsack. Now, I don't know how, he didn't realize and pulled up pretty hard, fifth grade, so not really hard, but still considerable. It hurt like hell, I blacked out for a moment and fell of my chair, at which point the teacher noticed.
Long story coming to an end, my friend from the other side of our table saw what happened and told the teacher, but somehow made it sound intensional, I suppose she didn't like the guy. I was taken to the school doctor and then to a real doctor, which coincidentally was the second and last time my balls were touched by someone other than me that day. While this was going on a witch hunt happened at the gymnasium, rumors spread and the guy had to go speak with our head teacher, and then the vice principal.
The day after I was asked to speak to the vice principal, before class and without parents there, and he basically asked me what happened. I can't remember what I actually said, this was some time ago, but I think I panicked and backed the story my teacher told everyone, of it having been intentional.
We never saw that guy at our school again, which I don't think is fair or the right punishment. I never spoke up, and two years later moved to Australia. I still think of this as the worst thing I've ever done.
Edit: shit posted my story with my porn throwaway, sorry