Shot myself with a BB gun when I was 12. To this day, still don't know exactly why it happened. I had a pump up gun, you know the kind - the more pumps the harder it would shoot. I had pumped this one probably a few too many pumps, went to shoot it, nothing. Trigger depressed, but no shot, no sounds at all. Tried to pump it again, but it was max'd out.
With no other ideas to try, i thought i would add some bb's and perhaps shake it or something. My gun was broke and i was going to try everything. The feed hole to pour in bb's was at the end of the barrel, near the muzzle. To open the hole cover, you rotated a ring which looked like a winchoke. Not realizing it, when I rotated the ring, my left pointing finger was directly over the muzzle. As soon as the feed hole was uncovered, the gun discharged and the bb hit my finger at max velocity. Holy $$$$!!!
It didn't penetrate the skin, but it sure felt like it had blown my finger clean off. It turned all shades of purple and blue. That gun got tossed into a corner and I don't ever remember shooting that one again.