During one kickboxing demonstration gone wrong, the instructor and an experienced student delivered blows to each other until the absolute grossest thing happened.
A low kick by the instructor caused the student’s knee to pop out of place, bending it in the wrong direction. While the injured student was in obvious pain, his bent leg prevented him from seeking comfort by sitting down…and I’m sure people’s laughter didn’t really help matters at all.
Be warned, folks. This is really nasty.