I received detention twice in my life, both for stupid reasons.

First one, I apparently didn't click the lock all the way on my PE locker, and the owners of any PE lockers left unlocked are given detention. I remember they would go around and pull on the locks to make sure they were all clicked in and locked and leave a detention slip in your locker if yours wasn't.

Second one, I walked into zero period as the bell was ringing, and since I wasn't in my seat by the time the bell rang, I was considered late. It was early in the year, and my teacher was doing the whole "start out strict, have less problems later" so made me go up to the office to get an unexcused tardy slip, which is equal to a detention. Interestingly, he ended up nominating me for a PTA award later in the year because I was his favorite student (he was not my favorite teacher, for unrelated reasons).