Green’s Dictionary of Slang

1. to fellate; occas. to perform cunnilingus.

1899		Crissie 132: ‘Damn it, I gammed her!’ echoed Piddlewick.
1910		I.L. Pavia Jahrbuch für sexuelle Zwischenstufen No. 11 40: [E]inige der gewöhnlichsten homosexuellen Ausdrücke [...] To bottle, to gam = Penilingus treiben [GS].
1960		J. Franklyn Dict. of Rhy. Sl. 108/1: Plate of ham Gam.
1966		T. Keyes All Night Stand 17: A mouth that God could have only made for gamming.
1972		B. Rodgers Queens’ Vernacular.
2001		I. Welsh Glue 41: She’s goat ma cock in her mooth n she’s suckin hard oan it, and by Christ, this lassie can gam.
2012		(con. 1980s) I. Welsh Skagboys 36: Ah’ve never been gammed like that before.
2015		I. Welsh Decent Ride 64: Some familar clients. There’s a wee guy who [...] eywis jist wants gammed.
2019		P. Baker Fabulosa 293/1: gamming oral sex.
2024		J. Meades Empty Wigs (t/s) 280: Saint Blaise... patron saint of the throat... and gamming of course [...] nature’s contraceptive.

2. (US campus) to kiss.

1987

Eble Campus Sl. Oct. 3: gam around – kiss passionately.