When I was at school there was a boy nicknamed Stooshy. I was extremely cruel to him once.
Someone had brought their dad's bongo magazines into the school. This was the 90s, and the mags were at least 10 years old. Pages stuck together, the works. Grotty as hell, but this was pre-internet so folk just had to make do.
Anyway, in our Techy Drawing class it was time to pass them on. I had had them for a couple of days. I handed then to Stooshy when the teaching assistant was out of the room.
She came back in, and as she walked past me I said, quietly enough for her to hear, "Check Stooshy's bag". A mate of mine heard me and repeated it. Then a couple of other boys did it too.
Stooshy went white. I mean, utterly utterly white. His face gave him away. The TA (who was actually very sound) went over to him and asked if he had any objections to her looking in his bag. He shook his head. And then she looked.
She said something like "I'll be right back", left with the bag and returned a minute later. She handed Stooshy his bag back, sans jazz mags.
To this day, no idea why I did that.