I still have a piece of graphite in my thumb from when I stabbed myself with a pencil when I was about 8 years old.
Ooh, here's a weird one. I used to be tongue-tied. The little piece of tissue underneath my tongue extended all the way to the end, and as a result, I couldn't stick my tongue out past my teeth. Due to a crazy teeth-brushing mishap, I ended up slicing that piece of tissue (I believe it's called the "frenulum") in half! Lots of blood and a few days of pain later, I was no longer tongue-tied.