It's not unique to our group, either. I just googled "bodily functions marathons" and there's all sorts of fun stuff like this gem. Or embarrassing moments while running. That's a good one. I've also heard about the "#2 tempo run" and bloody nipples (for guys) and black toenails but luckily those things never happened to me. I did have a toenail fall off once but I couldn't claim that trophy from running. My kitchen table just jumped out at me and its leg crashed down on my toe. For no reason. I still have a "baby toenail" growing back and I threaten to show it to my boys when they are acting up. "Look at the baby toenail!" "Ew gross Mom!"
When you are running for more than an hour, there's not a lot to talk about that is very stimulating. And the only way you find out about this stuff and how to deal with it is to talk about it.
So, what's your most embarrassing moment on a run or race? The worst I can claim is trying to throw a cup of Gatorade into the trash after the water stop and instead having the entire cup spill on me. Sticky gross mess for 5 miles.
Or what's the weirdest thing you've talked about on your run?