When I was around 7-9 years old, my little brother thought it was funny to close the closet door on me whenever I was in there. I remember getting tired of this and one day when my family and I were eating dinner, he went inside the closet to get something. To me, this was a golden opportunity to get back at him. Sure enough I did it, but his pinky finger for whatever reason was in the edge of the door or whatever. I don't know what it's called, but when I closed the door, it closed on his pinky finger and broke it. When I was little I also stole a Yu-Gi-Oh magazine and toy car once. Those are the only things I can think of at the moment that classify as "really" bad.