London, The Mean Fiddler, c1989.
Our guitarist decided to stage dive during one of his extended solos, as he launched himself forwards his forehead connected with the suspended PA stacks. He landed flat on his back, still on stage, out cold. The crowd roared thinking it was hilarious.
Our bass player was in hospital following a car crash two days before, so I was covering the bass for the night and found myself alone on a huge(ish) stage with just the drummer hiding behind his kit and the monitor engineer peering over the front of his desk from the side of stage wondering where the hell the guitarist had gone.... We kept playing.
After he hadn't moved for a few bars I thought it best to go and see if he was ok, we'd turned into a drum and bass band and it wasn't really working. I gave him gentle nudge with my boot... I think he groaned a little (couldn't hear much stood under the PA) then still flat out on the floor, eyes still closed, carried on with the solo as if nothing had happened.