Green’s Dictionary of Slang

French kiss n.

a deep kiss, using the tongue as well as the lips.

1919		F. Hurst ‘Oats for the Woman’ in Humoresque 78: Pressing a necklace of kisses round her throat [...] ‘One more, darling – a French one.’.
1936		M. Levin Old Bunch (1946) 180: She [...] gave him a long French kiss.
1943		R. Llewellyn None But the Lonely Heart 103: Give that there hokey pokey blokey a nice French kiss for me, will you?
1963–74		B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 82: Outside the door he receives a French kiss from attractive ‘model’ Germaine.
1966		P. Willmott Adolescent Boys of East London (1969) 45: She ran out after he tried to give her a ‘French kiss’.
1974		J. Lahr Hot to Trot 16: Rules of the Game – French kiss.
1987		‘Victoria Parker’ Pay for Play Cheerleaders 🌐 Then he broke the kiss and leaned over to Chrissie. Their wet mouths met in a fucking French kiss. His hand diddled her cunt.
1997		P.-D. Uys No Space on Long Street (2000) 114: sofie French kiss! You go too far!
2002		Chris Fothergill-Brown ‘WWE Confidential Report’ 30 Jun. 🌐 And The Rock used to put his arm around you, and we used to kiss a little bit. [Kissing the Rock = 1st base] We used to kiss a little bit, and a lot of tongue. You used to love The Rock’s tongue didn’t you? [Tongue = French kiss] [The British call it “Snogging].
2010		IOL News (Western Cape) 26 Aug. 🌐 Kissing with tongues has been known as ‘French kissing’ as far apart as Russia and [...] Britain.

In compounds

French kiss filter (n.)

(gay) any filter-tipped cigarette.

1972		B. Rodgers Queens’ Vernacular.
1986–7		Maledicta IX 55: French kiss filter n [R] Any filter-tipped cigarette; homosexual slang.