The worst was probably when I was in third grade, the summer before, really. We'd just moved into a new house in a new suburb and the roads weren't paved yet. I was riding along and saw a rock in the road, but it was too late to swerve. The wheel hit the rock and I went over the handlebars. The bike then went over me as I flipped and it landed on me.
Fortunately, I'd been taking Karate already and had learned how to fall. Instead of breaking anything, I managed to rip much of the skin off my left arm. I was bleeding all over the place, there was dirt and gravel in the wound, it was a mess. There I was, 8 years old, lying in the middle of the road, crying, screaming and bleeding profusely. Fortunately a neighbor heard me, came out, brought me in the house and cleaned me up and called my mom. I think I also got ice cream.
The most frequent accidents I ever got in were my brother's fault. He is 2 years younger than me and I felt responsible for him and also had to make sure I didn't lose him. At least 3 times when we were out riding, I'd look back while riding at high speed to see how far back he was and turn back around just in time to watch myself ride into a parked car. I'd go over the handlebars every time. Once this was on a busy street and I looked up to see a car stopped with me right in its path.
Now it is your turn! What's the worst bike accident you've ever had? Tell me in comments.