Let's talk about times you got in big trouble when you were a little kid. (or hell, when you were an adult.)
When I was in second grade I shoved a kid into a locker, shut it, and locked it. No one knew the combination and the custodian had to come break the thing open. Yeah, I got in big trouble for that. The weird thing is that I have no idea why I did it. The kid was a good friend, and we were still friends after the incident. I think I thought it would be funny or something.