Ok, I am exaggerating probably. But I have heard the most frequent question to astronauts is related to going to the bathroom.

Here is a interesting article, that is not too graphic in description. Needs imagination though of life in zero-G.

http://www.lifeslittlemysteries.com/how-do-astronauts-go-to-the-bathroom-in-...

Samudra, N3RDX & S21X