Green’s Dictionary of Slang

sexual intercourse.

1955		T. Williams Cat on a Hot Tin Roof Act II: Was it jumping or humping that you were doing out there? What were you doing out there at three a.m., layin’ a woman on that cinder track?
1966		(con. 1958) R. Farina Been Down So Long (1972) 62: ‘She’s down on humping, is she?’ ‘Intercourse,’ corrected Fitzgore in despair.
1970		E. Thompson Garden of Sand (1981) 299: He was older than Allen and his cow-humping old man.
1984		S. King Thinner (1986) 76: The only things men like you understand are humping, [...] and how to bet on pro-football games.
1997		(con. 1960s) A. Frewin London Blues 144: He wants some 10-minute films . . . all the usual ingredients . . . plenty of humping and that.
2001		Source Aug. 196: You’re left with gun talk, ass-kicking, humping and being high.
2008		J. Lansdale Leather Maiden 68: ‘I got the romance with her.’ ‘What you got was some humping’.