Got blocked in the back during a junior varsity football game my sophomore year; broke the scaphoid in my right wrist. My high pain tolerance led to my believing it to be minor; I played the remaining three+ quarters of that game. Afterwards we got it x-rayed. They put a cast on it for six weeks, took that off and performed more x-rays, put a cast on for a further six weeks, and only then realized that it was not healing. Had to have surgery, which went well.
Hyper-extended my right knee during my senior year; played through it and was fine.