Green’s Dictionary of Slang

(orig. US) cunnilingus.

c.1931		in P. Smith Letter from My Father (1978) 256: Few American men understood the fine art of preliminary stimulation, how necessary it was for the female and how ‘cunt-lapping’ helped.
1941		G. Legman ‘Lang. Homosexuality’ in Henry Sex Variants 1 162: cunt-lapping is the verbal noun for cunnilinctus.
1969		‘R. Titan’ Hollywood Switch-Hitters 182: ‘Yes, and let’s keep our cunt-lapping and eating for a real long time’ [Simes:DLSS].
1971		J. Jones Merry Month of May (2004) 55: His own young porno collection had swung more and more toward [...] material having to do with cunt-lapping.
1998		‘Bill E. Goodhead’ Nubile Treat 🌐 From a playful little game, the cunt-lapping had become very much in earnest.