Green’s Dictionary of Slang

1. (orig. US black/W.I.) to have sexual intercourse.

1946		in Randolph & Legman Ozark Folksongs and Folklore (1992) II 707: Mama’s layin’ on her back, / Papa’s up on top, / Baby’s in the cradle / Hollerin’, ‘Jam it to her, pop!’.
1967		K. Kolb Getting Straight 95: I got so tired of all those fays and gays jammin’ each other.
1978		P. Theroux Picture Palace 92: ‘Jammed.’ ‘With your daughter?’ ‘With my sister [...] Got no daughter.’ I said, ‘I don’t think you ought to be telling me this, Mister Teets.’.
1980		M. Thelwell Harder They Come 228: Roy, him don’t say nothin’, him just a grunt and jam.
1999		Guardian Guide 29 May–4 June 15: Charlie Sheen declaring his desire to ‘jam’ her.

2. in fig. use, i.e. euph. for fuck v. in a variety of senses.

1975		E. Torres Carlito’s Way 3: The Puerto Ricans been gettin’ jammed since the forties.
2005		M.B. ‘Chopper’ Read Chopper 4 173: But as far as I’m concerned / They can jam their Johnny Cash.

3. (US black/gay) to have anal intercourse.

1996

L. Pettiway Honey, Honey, Miss Thang 145: Most of them were like put the grease in, just go ’head and jam you, you know.