Likely a reference to a Bugs Bunny catch-phrase:
https://www.youtube.com/watch?v=_NYFq7ZJg4cI always thought maroon was actual slang for "idiot", when in fact it was just a cartoon rabbit ironically mispronouncing the word moron.
Bugs Bunny is also the reason "nimrod" has become slang for an inept person. Nimrod in the Bible is a powerful warrior and capable hunter, but Bugs used it ironically against Elmer Fudd.