Green’s Dictionary of Slang

1. the penis [pun on rod n. (1)].

1890–1904

Farmer & Henley Sl. and Its Analogues.

2. (orig. US campus) a socially inept person, someone not attuned to the group norms [popularized by 1940s Warner Bros. cartoon character Elmer Fudd (a rabbit-hunter), called ‘poor little Nimrod’ by Bugs Bunny].

1933		Hecht & Fowler Great Magoo 183: He’s in love with her. That makes about the tenth. The same old Nimrod. Won’t let her alone.
1993		Tarantino & Avery Pulp Fiction [film script] 157: If you give this nimrod fifteen hundred bucks, I’m gonna shoot ’em on general business.
1997		C. Hiaasen Lucky You 219: He couldn’t believe these nimrods—the concept of ethnic purity wasn’t that complicated.
2023		(con. 1962) J. Ellroy Enchanters 138: ‘Bob Bereglund is a nosebleed, a nimrod, a ho-daddy and a pseudosurfer’.