TIL that Dunning and Kruger were

inspired by McArthur Wheeler, a Pittsburgh man who attempted to rob a bank while his face was covered in lemon juice. Wheeler had learned that lemon juice could be used as "invisible ink" (that is, the old childhood experiment of making the juice appear when heated); he therefore got the idea that unheated lemon juice would render his facial features unrecognizable or "invisible."

https://rationalwiki.org/wiki/Dunning-Kruger_effect