When I was eight years old, I had a bicycle. It was a nice, early 1980's style bicycle with a banana seat. One day, my friends and I were having races around Gingko Drive on McChord AFB. I went first, and got around fairly quickly. My friend went second, and he beat me. Not being one to like being beaten on my own bicycle, I went around a second time.
Things were going great. The sun was shining, just a couple clouds out, there was a slight tailwind, which helped me on the first leg, and I had managed to really get my bike around the first corner without losing much speed. I knew I had a chance at beating my friend, I just had to really nail the corners (he had bigger legs than I, so he could beat me on straightaways, I needed cornering speed to remain competitive). So as I came up to the second corner, I noticed a little dip on the side of the road where the sewer is slightly indented for the water to flow in. Now, I didn't know much about physics, still don't, but I knew that things tended to go faster around raised curves, and I knew that I could turn faster at a lower angle by using the dip in the street.
So that's what I aimed to do, and I hit the dip perfectly, I started my right turn, leaned my bike all the way down so that I could really use the centrifugal force, and I happened to notice that my right pedal was down, instead of my left. I thought to myself, "I should probably have my other pedal down, because my turn is so low, my pedal might hit the pavement." Actually, I didn't so much think that to myself as realize it about a nanosecond before it happened.
I don't remember how I got home. I don't, really, remember the visit to the doctor that day, but I do remember my parents having to ask me every two hours who I was and where I lived. I got the answers right.
Perhaps I should have started wearing a helmet after that.