It's something we all think about and fear, but never talk about it. Until now.
My underground toilet kit: saran wrap, toilet paper, ziplock bags (2).
Unfortunately, my planning did not count for one thing: what to do with the bag. See, underground is very dangerous place for items that can be smashed, punctured, or damaged by water.
Solution: put it in my helmet. Nice and warm. Extra padding too! The s**thead jokes afterward were just a bonus.