Caught naked by male teacher
I've never told anyone this, but when I was in middle school, we had a swim class. One day, I was in the locker room with the other girls of my class, showering and getting changed back into our regular clothes, and a friend and I noticed that there was a door on the opposite end of the locker room, and we were curious where it went.
Completely naked, we opened the door and found that the door brought us out into one of the hallways. Unfortunately for us, a moment later a male teacher rounded the corner into the hallway and caught us. Needless to say, we got in a lot of trouble.
At the time, the idea of being naked in front of a male teacher was mortifying, but now it's just so fucking hot to me that it happened.
Something similar happened to me but at a summer camp. If I think about it, the whole shoulda woulda coulda ideas i get drive me crazy.