Green’s Dictionary of Slang

(US) the female breast; usu. in pl.

1966		Trimble 5000 Adult Sex Words and Phrases.
1976		E. Thompson Caldo Largo (1980) 101: I am a big ass, chi-chis, a cunt, something to put on a bed. [Ibid.] 119: I will introduce you to my wife’s friend with the big chi-chis. Big, man!
1981		J. Ellroy Brown’s Requiem 143: This feeling was quickly engulfed by a wave of sweaty lust—directed at Sister Kallie and her big chi-chi’s.
1990		S. Morgan Homeboy 20: Big ass and chichis is all you love.
2000		P. Beatty Tuff 98: You wait a bit, look at your watch, and say, ‘Forty-five minutes, and this bitch ain’t showed no titty? This flick sucks.’ If she flash her chichis before fifty-five minutes, then the movie really sucks.
2010		J. Ellroy Hilliker Curse 7: Her big chi-chis shook.
2021		J. Ellroy Widespread Panic 70: I poured her Tom Collins down her dress and ice-cubed her chi-chis.