Worst I ever saw had to be the first day of the season about two years ago. I was with some roommates at the time who are all about the park. I'm not a big park kind of guy, but I went in with them to watch them hit the rails. While we were there, I saw a guy try to jump on a box, but his nose hit the front of the box and he went flying face first into the top of the box. He must have smashed out every one of his front teeth on that box. He was a bloody mess. Pieces of his pearly whites were everywhere and he was still concious somehow. He got up and spat out an entire mouthfull of blood.
Needless to say, I'm sure that guys dentist was happy. Everyone wants dentures at 22 right? lol