please tell me the most obscure joke you know

(feel free to explain or not explain it, depending on what you find more amusing to think of me reading it)

@whitequark Q: What's an anagram of Banach-Tarsky?

A: Banach-Tarsky Banach-Tarsky.

@ljrk
@whitequark Here to drop in the oldie goodie https://youtu.be/uFvokQUHh08
Matematikrevyen 2011: Banach-Tarski

YouTube