A relevant story I posted last year in another thread:
Three years ago I was night skiing at my local hill where we had a pretty decent jump line happening. Three jumps: 35', 40' and 45'. I had been doing some spins over the first one that evening and thought I'd take my tricks to to the next jump that was a little bigger. I came in fast to the second jump, wanting to do a 3, but due to extremely variable snow conditions on the North Shore mountains I lost a bit of speed as a I hit the lip. I completed the spin but cased, smashing my ass on the heel piece of my left binding. I slid down the landing in considerable pain holding my ass in attempt to try and minimize the pain. My buddy skied down to where I was lying in the snow and helped me up. As I was standing up I said, "Bro, there's something dripping down my leg. I think my ass hole is bleeding."
Like any good friend, he laughed at me, shouting out to other random skiers, "This dude just popped his butt cherry!"
It would have been funny, but I was in a lot of pain. As I skied down to the lift line (still holding my ass) to go up to the cafeteria and see what the hell was wrong with me, I noticed that this blood coming from my ass was now dripping into my ski boot. Slightly grossed out at my self, I got on to the lift and made my way in agony to the cafeteria wash room.
Once in the wash room I dropped my drawers to check out what the hell I had done to my self. As it turned out, I had not tore my ass hole open and was not bleeding, but I had completely shit my pants.
After a smelly car ride home and a miserably painful sleep, I went to the doctor the next day. I told him my story. He laughed at me. He also told me how there is a nerve in your lower back, and if that nerve is pinched it releases all the muscles that control your bowel movements. So when I cased that jump, my bowels released and I uncontrollably shit my self for an hour. The end.
TLDR: Cased a jump, thought my ass hole was bleeding but I was actually was just shitting my self uncontrollably.