In a moment of youthful exuberance I lept off the stage, executed a perfect scissor kick and smacked my head against a low beam. No blood, but I was a bit fuzzy for the next couple of songs with mild concussion.
I did once look behind me just in time to see the drummer disappear down the gap at the back of the stage along with his drum stool and whatever bits of kit he tried to grab on his way down. Luckily it was only a couple of feet drop