I know there have been similar threads on this, but I Searchbarred and didn't find any that had more than 2 stories and they were usually about crashes. Here's my contribution:
Vail Resorts Ski School used to have something called the Extreme Skiing Workshop. It was Chris Anthony's deal, and I was one of his coaches. It turned into almost like a vertical feet challenge with basically non-stops in the bowls all day long, with about a 15 minute lunch break.
One day only one guy shows up for the workshop and he tells me he just wants to get as many runs as possible. This statement would prove to be very ironic. We basically ski our asses off all day and at the end of the day we are coming up Chair 5 and the guy tells me he is going to have to hit the bathroom at the top of the lift. He explains that it is pretty urgent. I thought he had to piss and jokingly told him he could always go on "manual hold". He said that it was actually the other problem. "Oh".
We get off the lift and he starts skating as fast as he can over to the bathroom, but he slows down and I feared the worst. He goes into the bathroom and doesn't come out again for over half an hour. When he comes out, he tells me that he didn't quite make it. The guy had been wearing a one-piece suit and had basically filled it up. He had just thrown his underwear and longjohns in the toilet and had done his best to clean out his suit.
The guy had a pretty good sense of humor about it. When he told me what happened, the only thing I could say is "Shit happens". He said that he "still felt pretty crappy about the whole thing". Basically I think that we skied so hard that certain muscles kind of gave out. Secretly, I became known as the only instructor in Vail who had actually skied the "living shit" out of someone.