In contemporary U.S. slang, "nimrod" means "fool, numbskull".
Rex Knepp ingeniously suggested that the origin of this was Bugs
Bunny's taunt of Elmer Fudd: "So long, Nimrod." Unfortunately for
this theory, Jesse Sheidlower says that Random House has two
citations of "nimrod" = "numbskull" from the 1930s, before the Bugs
Bunny episode containing the taunt.