Green’s Dictionary of Slang

1. an echoic excl. used to imply suddenness, of a statement, an action etc.

1955		B. Schulberg On the Waterfront (1964) 178: The third time I tried it the gag worked and boom! out shoots the drawer.
1962		P. Crump Burn, Killer, Burn! 50: He pops you punks to a bottle of wine [...] and rides you around in his ol’ man’s Caddy and boom! That makes him an all-American boy.
1973		S. Saddler in Heller In This Corner (1974) 288: Surprisingly, for chrissakes, boom, it was so.
1974		V.E. Smith Jones Men 133: He kinda just threw it out whole he was rappin’ and boom! he kept right on goin’.
1980		Eble Campus Sl. Fall 1: boom! – expression of happiness at having achieved something.
1995		(con. 1985–90) P. Bourjois In Search of Respect 121: Everytime they sent me to some company, boom! I’m hired.
2000		C. Cook Robbers (2001) 55: Now boom, homicide. A giant leap forward. Not your usual career move.
2011		W.D. Myers Carmen 54: No fingerprints. No DNA. Just get in and boom, boom, boom!
2024		D. Swierczynski California Bear 26: She’d file her papers through the school server, and boom, she’d be a sophomore.

2. (US black) a general excl. of agreement.

1994

C. Major Juba to Jive.