Green’s Dictionary of Slang

(US) a pest, a fool, an insignificant person; also as adj.

1925		A. Yezierska Bread Givers 126: ‘Nag! Noodnik!’ Father turned upon Mother. ‘Stop making me miserable.’ [OED].
1941		A. Kober My Dear Bella 74: You hear me, Mrs. Nudnick, you!
1953		A. Kahn Brownstone 158: The more lackadaisical men and women in the club mumbled at her as a ‘nudnick’ because in her devotion she never forgot when someone made a pledge.
1955		Mad mag. Jan. 8: You and your blasted relatives ...them three little noodnik ducks!
1964		J. Charyn Once upon a Droshky 152: The nudniks came all the way over from Rivington Street.
1976		J. Rosenthal Bar Mitzvah Boy Scene 66: You thought you’d get it all wrong! That you’d make a nudnik of yourself!
1985		Singer & Burgin Conversations with Issac Bashevis Singer n.p.: The writer who writes about himself all the time must become a bore, just like the man who talks all the time about himself. When the writer becomes the center of his attention, he becomes a nudnik.
1997		Eble Campus Sl. Apr.
2002		J. Ellroy ‘The D.A.’ in Destination: Morgue! (2004) 140: Six notable new-left nudniks lay dead.
2021		J. Ellroy Widespread Panic 49: It was all for Confidential. [...] You naïve nudniks know that.