“The calluses on your feet in space will eventually fall off,” astronaut Scott Kelly revealed in a Reddit AMA. “So, the bottoms of your feet become very soft like newborn baby feet. But the top of my feet develop rough alligator skin because I use the top of my feet to get around here on space station when using foot rails.”

Floating calluses with the potential to enter an unaware, open mouth is enough to irk most people, but that’s not the worst of it. Take what happened during STS-1, for example.

In April 1981, astronauts John Young and Robert Crippen piloted the Space Shuttle Columbia successfully through its maiden mission, but not without a few hitches. The toilet clogged early on, forcing the two crewmembers to use fecal containment systems, long, tube-shaped bags affixed to the buttocks with a sticky seal to trap, and store, evacuated feces. Even worse, during re-entry, vacuum-dried fecal matter from the broken, bloated toilet migrated to the ventilation system and entered the main cabin. Young and Crippen survived the poop particles and soldiered through the *ick* factor in professional fashion.