Both of these are actually caving trips, but they're both pretty stupid, so...
I once visited a certain mine shaft which has a scaffolding platform installed at a landing about 50m down. In my haste to get down there I managed to abseil myself onto the end of one of the upright tubes, landing on my coccyx. It hurt too much to even shout - I think I may have just cried like a kid and had to lie down for ten minutes to get over it. I didn't dare look at the time but I could tell it wasn't dripping blood, so carried on with the (5 hour) trip. Not surprisingly I had the bruise to end all bruises when I got my kit off, and a nicely chiselled impression of a tube corner which stayed for days and it hurt for weeks. Next time up there I took a carrier bag, which I stuffed into a ball in the end of the tube to soften the impact should anyone else do the same thing. I think it's still there.
Oh, and on my last digging trip into Nixon's Aven in Peak, only a few months ago, I picked up a big slab of rock to move it out of the way as it was dangerous, and trapped the tip of my little finger between it and the wall. That was another delayed trip to the hospital, another 'disappointing' X-ray and another no-fix situation. They even gave me a tetanus jab and five days of antibiotics when I told the nurse I did it in a cave. To be fair it was twenty years since I'd had a tetanus, so it was probably time for an update. But that was another two weeks off.
I do generally do a lot of trips though, so my annual average of accidents, above ground or below is still pretty low. There's still time.