I went to a comedy show today with my family and it started with a line about the Banach-Tarski paradox.

I can never hear about the Banach-Tarski paradox - which has surprisingly happened a couple of times - without thinking about where I first encountered it, namely as a safeword in Harmonic Function, a McShep kinky smut fic by shaenie. It's funny (and a little awkward) every time.

(The comedian explained Banach-Tarski and then said it basically applies to problems: if you have a problem and separate it into two problems, these problems can both be as big as the original problem. Sad but true.)