I once head-butted a basketball pole. I was landing from a jump and leaned forward hard to keep my balance...right into the pole. My vision went white for a few seconds, and I stumbled around a bit. Scalp wounds are bloody, kids. I still have a scar, but you can't see it under the hair.
I also once burned a finger on a car cigarette lighter. Fuck, that hurt. Still have the scar.
Then there's the time I fractured a finger when a basketball hit it head on while my finger was rigid. Couldn't make a fist for like two weeks after that.
Incidentally, all three of these events happened in the same year, in junior high. I haven't experienced anything that bad since, besides the occasional party where I drink too much and pledge to God that I'll never take another sip if he just lets me live through the night

.
Oh, but there was the time in grade school that I put a staple right through my fingernail. That hurt a bit as well.
I'm actually not that accident-prone, believe it or not.