In junior school, a friend thought it was really funny to bring in a chilli and give it to me to eat - I'd never seen such a thing. Nearly broke my neck skidding into the toilets to dunk my head in cold water. Had a bad neck and sore mouth for about a week, I was 8.
My brother shut himself in the door of his car, slammed it against himself and caught his hip, covered in bruises and his back's not been right since.
Dancing (drunk) with a mate, I stepped back as he went to cuddle me, I tripped backwards over a step in the pub and hit the back of my head square on a corner of the wall.
Bled like a bastard (being pissed probably made it bleed more) and my (now ex) DP came home to find a man from the pub had taken me home, him sitting watching our telly with me passed out beside him.
Awfully irresponsible really, this happened the Friday night and I went to work on the Monday and had a minor breakdown over a car parking space, nurse diagnosed concussion and sent me home. My hairdresser still remarks on the impressive scar, though I had no stitches.