From being a kid:
Dropped a metal bowl with flat edges on my right foot when i was young, barely remember it. All I do know is that bowl is somewhere in the house, and I have a scar on my right foot, on that toe beside the largest one. Never did learn the specific names of toes (could I call it my index toe? Hmmm...)
Cutting the bad spots out of carrots wrong, the knife slipped and put a nice scar on my left index finger.
Early teen years (wasn't an adult, therefore still counts), swinging a plastic scythe around, generally being an idiot, smacked myself maybe an inch away from my left eye with the back of the thing, which had spikes on it. Good job, I know >_<
Another fun teen story: Tripped on a gap in the crosswalk maybe a centimeter or so wide, and landed on ice and cement. Had to go in for surgery on my right knee due to it breaking and going back a good 3 mm.
Still in them teen years, got jumped and the assholes broke my cane over my head. Got a nice scar in my hairline near the back of my head from it.
Now for the adult ones:
Walking home from work, was looking down at my mp3 player. It had been a particularily draining overnight shift, wasn't really paying attention to the route (I walked it so often I had kinda memorized it.) Walked into the back of the highway sign on the way home, and put a nice hole in my head. Didn't realise it was bleeding till I got to the crosswalk XD
Another fun one, was putting a knife away in the hip holster I had on, and wasn't looking to see if it had gone in properly or not. Turns out it hadn't even gone in the sheath, and I dropped it on my foot >_< Ah, to be 18 and an idiot...