My worst injury was tearing the ligaments in my thumb (all of them) while playing goalie at a soccer game. They had to cut my glove off, and I was in a cast for 6 months. THEN I played a game of indoor soccer, with a soft cast, and this huge fat chick landed on me, on my thumb, and back in the cast for another 3. I was pissed.
My friend's worst injury was on the 4th of July. He had a nerf-gun, stood at the top of the stairs, screamed "FOR GONDOR" and jumped down the stairs, resulting in two broken ankles.