Some of the things I have done:
One day when I was about 7, for reasons as yet unknown, my front wheel just stopped turning. It was like the road suddenly got mad at me, spun around and hit me in the face. I wondered home with about three fewer teeth than I had before and a huge gash in my forehead gushing blood.
I jumped off of some stairs
I was running down the stairs to the basement. To avoid the last three or four steps I lept. The plan would have gone off without a hitch were it not for the steel i-beam that rammed into my forehead. My body flew out from under me and I fell, landing perfectly flat on the uncovered cement floor. I think this was the most painful thing I have experienced to date.
I was helping my dad top a tree in our backyard. It was a big, dead birch tree with a funny twist in it. If it were cut at the bottom it would have become caught in the other trees. My job was to pull on a rope that was tied to the top of the tree to prevent it from falling directly away from me (we were trying to get it to fall perpendicular to the direction I was pulling). I was rather young at the time and holding onto the rope was hard, so I tied it around my waste. It worked like a charm. :)
After my dad had cut most of the way through the tree he came down and helped pull, not knowing what I had done. When the tree fell down it fell perpendicular to the direction we were facing as we pulled. Everything seemed fine at first, but then the rope caught on a branch and I went shooting along the ground like a rag doll. I tripped my dad with my face as I didn't have time to move my arms to block. The only thing I saw were the backs of his legs as they suddenly come bolting at my face.