Green’s Dictionary of Slang

usu. in pl., the female breasts.

1967–8		Baker et al. CUSS 129: Grapefruits The female breasts.
1972		R.A. Wilson Playboy’s Book of Forbidden Words.
1982		Maledicta VI:1+2 (Summer/Winter) 132: Chichi (breasts, boobies, grapefruits, headlights, lungs.