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.

PUMPKIN
About fifteen hundred dollars.

JULES
Put it in your pocket, it's yours.
Now with the rest of them wallets
and the register, that makes this a
pretty successful little score.

VINCENT
Jules, if you give this nimrod
fifteen hundred buck, I'm gonna
shoot 'em on general principle.

JULES
You ain't gonna do a goddamn thing,
now hang back and shut the fuck up.
Besides, I ain't givin' it to him.
I'm buyin' somethin' for my money.
Wanna know what I'm buyin' Ringo?

PUMPKIN
What?

JULES
Your life. I'm givin' you that
money so I don't hafta kill your
ass. You read the Bible?