Oh god, I had a guy on work practise a couple of weeks. He was about 15, and pressed capslock, another key, and then capslock again for capital letters.

I suddenly stormed into the room screaming, with a knife. I plucked out the capslock key, and ran out of the room, still screaming. Then I popped my head back in through the door in a much calmer fashion and told him he would get the key back after his practise time at our company.