I've never been seriously injured, but about a year ago I cut the end of my index finger off while ajusting the disc brakes on my mountain bike. I had the bike upside down, and spun the pedals as fast as I could in top gear. While trying to center the disc while the wheel was spinning, I was careless and jammed my finger into the disc, which haulted the wheel immediately. It was dripping blood, and hurt quite bad. But the real painful part was waiting 18 hours to get it stitched back together (free healthcare=long wait for non life threatening injury ).
I also got a freak injury about 5 years ago while bowling; while throwing the ball, a huge spliter jammed between my finger and my nail. That hurt like a bitch. Getting the needle shoved in my finger to freeze it hurt just as much as the injury itself, as the doctor was twisting and spinning the needle in my finger and I could hear and feel my bones crunching... kinda weird that both my worst injuries happened to my fingers.