I've got a few weird ones for people I know, not so many for myself...
I took nearly all the skin off the bottom of my big toe when running up the stairs. I didn't move my foot far enough onto the step, so only my toe got any ground. Thus, when I put all my weight and inertia on that solitary toe, it grinded down to the next step, taking most of the skin off. Man that hurt.
Not so much an injury, but this one happened when I used to fix watches. I was at work, minding my own business when my nose started to bleed heavily. Because I was the only one working at the time, I couldn't go anywhere to deal with it. So I'm standing behind the counter, my hands and face covered in blood and the bin beside me filling with reddened tissues, when a customer arrives. He looks at me, and demands I fix his watch immediately. People are compassionate aren't they?
My cousin has a spectacular one though. When we were younger I used to have a little pedal Formula 1 car. My cousin, brother and I were riding it down the grassy hill beside my house. Also on this hill was a rather large patch of sticks (still not exactly sure what it's there for...). So my cousin takes his turn, looses control of the car and ends up riding over the stick pile. Suddenly he jumps out of the seat screaming in pain- one of the sticks has flicked up, pierced through the fiberglass seat, through his pants and impacted millimetres from his butthole. Yeah.
EDIT: Just remembered another one. I was at school and my stapler had jammed. I'd been trying all lesson to fix it, but to no avail. So, I decided to scare my friend by sticking my finger under it and hitting it. As you may have guessed, the stapler decided to work that time.