There is also the Poynting Vector [1] named after John H. Poynting [2] that "points" in the direction that electromagnetic energy is flowing.

[1] https://en.wikipedia.org/wiki/Poynting_vector

[2] https://en.wikipedia.org/wiki/John_Henry_Poynting

Sadly not quite in the same vein, but the Killing field seems rather vicious until you know it's just named after Wilhelm Killing. (EDIT: Sorry, I didn't notice klyrs mentioned it 2 hours ago: https://news.ycombinator.com/item?id=23890735 .)

Or Čech cohomology, usually denoted with the check "v" above characters.

I don't have a clue about the math, but I liked the puns in the preface to Knuth's "Concrete Mathematics":

"When [Knuth] taught Concrete Mathematics at Stanford for the first time, he explained the somewhat strange title by saying that it was his attempt to teach a math course that was hard instead of soft. He announced that, contrary to the expectations of some of his colleagues, he was not going to teach the Theory of Aggregates, nor Stone's Embedding Theorem, nor even the Stone-Čech compactification. (Several students from the civil engineering department got up and quietly left the room.)"

https://en.wikipedia.org/wiki/Stone%E2%80%93%C4%8Cech_compac...

It's a joke between students of quantum mechanics that to get operator from a function according to the principle of least action you have to put "^" above the function name.

(Čech means "a Czech person")

I thought so, but thanks for doubleczeching.