Experiment
When I was about 11, my youngest brother who was about 4 was standing on the down end of an improvised see-saw we'd constructed just for fun. I immediately jumped onto the other end as hard as possible. Needless to say, he went straight up into the air, did a flip, and landed on his head (I wanted to see if it would work like in the circus). No serious injury, but he was really angry. I also pushed my younger brother (then about 6 or 7) off a slide and broke his collar bone. I also threw a pinecone at my sister's face. You have no idea how much blood that makes. Fun times - we are a very violent family.

Also my first posting after ages of lurking and reading the questions. The barfing QOTW was the one I read first...
(satellite blows, Wed 24 Aug 2005, 9:35, Reply)