Green’s Dictionary of Slang

1. to reach orgasm.

c.1930

‘Mickey Mouse and Donald Duck’ [comic strip] in B. Adelman Tijuana Bibles (1997) 41: Give it to me, you sweet little rat – I’m going to go boom-boom.

2. (US, also boom) to have sexual intercourse.

1987		Eble Campus Sl. Spring 1: boink – have sex. [...] Also boom.
1990		(con. c.1970) G. Hasford Phantom Blooper 48: We said, ‘Baby-san, you boom-boom?’ And she giggled, remember? She said, ‘You give me beaucoup money.’.
2003		A. Herz Amer. Wedding [film script] It’s time for me to boom-boom with the bridesmaids.