Green’s Dictionary of Slang

1. to watch (a gambling game) and to comment/advise but not to participate.

1927		in AS IV:2 (1928) 159: It [a trade journal] defines ‘kibbitzing’ as a slang expression used to indicate the act of offering gratuitous advice by an outsider.
1934		T. Minehan Boy and Girl Tramps of America (1976) 109: There is a checker tournament in progress [...] three different players shouting aloud and a crowd laughing and kibitzing.
1944		D. Runyon Runyon à la Carte 203: Schultz kibitzes the captain on one hand and me on the next.
1952		(con. 1920s) ‘Harry Grey’ Hoods (1953) 182: Max took a hand for a while and the rest of us kibitzed.
1956		‘Charles Raven’ Und. Nights 9: He came over to our table and kibbitzed at the Klobbiotsch for a while.
1960		(con. 1905) R. Barber Night They Raided Minsky’s (1968) 145: One day in 1905 he was discovered kibitzing a pinochle game.
1974		(con. 1940s) E. Thompson Tattoo (1977) 50: They had silently kibitzed the old men’s domino games.
1985		(con. 1968) D.A. Dye Citadel (1989) 53: Crews working with slick precision, showing off for the kibitzing grunts.
1991		(con. 1920s) O. Dexter Brooks Legs 195: The game was spirited. I stood and watched until the I heard the living-room clock chime eight. Tired of kibitzing, I went to the hall to get my coat.
2002		J. Lerner You Got Nothing Coming 79: More black Fish Tank guests surround the table kibitzing or just kickin’ it with their homies.

2. (also kibetz) to chat, to gossip, to pester, to cajole.

1929		S.J. Perelman in Marschall That Old Gang o’ Mine (1984) 62: Sally Gaffney, 3, was kibetzing around with Aaron Apple, 2, several days ago.
1939		R. Chandler ‘Pearls Are a Nuisance’ in Spanish Blood (1946) 107: I never kibitz the cops.
1950		B. Spicer Blues for the Prince (1989) 169: Siddown, friend. Let’s kibitz awile.
1968		P. Barnes Ruling Class I xv: If you want to keep kibbitzing here, belt up on the snide remarks.
1978		L. Kramer Faggots 52: If they didn’t like the movie, they would kibbitz in the darkness.
1987		T. Wolfe Bonfire of the Vanities 659: The District Attorney would not respond to ‘kibbitzing’ by ‘someone no longer involved in the case’.
1990		S. Morgan Homeboy 75: ‘Pack that meat in, you cumsuckin bitch!’ kibitzed the comic.
2000		P. Beatty Tuff 9: The poor, whining creatures, left tethered to parking meters while their owners kibitzed over cappuccino.
2023		(con. 1962) J. Ellroy Enchanters 210: Pali High girls kibitzed and swooned.