Green’s Dictionary of Slang

1. (also dry root, dry run) to simulate intercourse; thus dry humping n.

1961		T.I. Rubin In the Life 70: They dry run you. [...] It’s a standing up trick, with out putting it in. The poor jerks have to pay before they pop.
1974		(con. 1960s) R. Price Wanderers 101: ‘D.H.T.I.C.’ which stood for ‘Dry Humped Till I Came’.
1986		L. Heinemann Paco’s Story (1987) 13: That broad shimmied and pranced [...] dry-humping the air with sure and steady rhythmic thrusts of her nifty little snatch.
1990		S. Morgan Homeboy 44: One can dry hump the local roundheels without fear of infection.
2002		Coren & Skelton Once More With Feeling (2003) 66: I grew up in the 1950s [...] The status symbol in those days was dry humping, which I still like.
2003		www.thepantsman.com 🌐 After dry-rooting for three or four songs, I decided it was time to go for gold. [Ibid.] Pressing her up against the wall like a piece of art for a snog and a dry-root.
2010		Codella and Bennett Alphaville (2011) 59: Some couples had parked away from the streetlights and were dry humping and making out.
2015		P. Beatty Sellout (2016) 69: We thought that he was being funny, dry humping the TV with every low-angle shot of Darla’s exposed lace panties.

2. in fig. use, to exploit, to do something that inevitably fails.

1975		E. Torres Carlito’s Way 49: They dry-humped you with a couple of quarters — you was a nickel-and-dime hustler.
1989		C. Hiaasen Skin Tight 218: All it took was three hours of dry humping these islands.