Green’s Dictionary of Slang

buttfuck v.

also b.f., butt-bang
[butt n.1 (1a) + fuck v. (1)/bang v.1 (2a)]

1. (US) to subject to anal intercourse; thus buttfucking n. and adj.

[US]B. Rodgers Queens’ Vernacular 87: anal intercourse [...] BF (kwn Southwest, early ’60s, acronym for butt fuck: ‘I’ve never BF’ed anybody before, man’) [...] butt-bang [-fuck] (mid ’60s).
[US]L.K. Truscott IV Dress Gray (1979) 471: The butt-fucking and cock-sucking that went on.
[US]C. Hiaasen Tourist Season (1987) 130: He’ll be in the Betty Ford Clinic while you and me do twenty-five at Raiford, gettting butt-fucked in the showers.
[US](con. c.1970) G. Hasford Phantom Blooper 12: Every twenty meters I stoop down and tug at the barbed wire [...] The tugging scares up bunker rats big enough to stand flat-footed and butt-fuck a six-by.
[Aus]B. Moore Lex. of Cadet Lang. 68: usage: ‘He then said “Bite the pillow, bitch!” and butt fucked her’.
[US]J. Stahl Perv (2001) 305: Maybe he’d been BF’ed by smacked-out hippies in the back of a car.
[US]T. Parker South Park: Bigger, Longer and Uncut [film script] kyle: Don’t call my mom a bitch, you fat fuck! cartman: Don’t call me fat, you buttfuckin’ son of a bitch!
[US]C. Hiaasen Skinny Dip 112: I’m the sumbitch gonna butt-fuck those puppies, you don’t clean the piss off my tar.
[US]Simon & Burns ‘Screwby’ Generation Kill ep. 3 [TV script] Using this lubricant is like trying to butt-fuck a virgin underage Phuket whore with chalk. KY is clearly called for.
[US]G. Hayward Corruption Officer [ebk] cap. 27: Telling him [...] some other man is butt-fucking his girl right now, etc.

2. in fig. sense, to treat unfairly, to cheat, to deceive; thus buttfucking n.

[US]Maledicta III:1+2 55: Males in particular [...] who have been denied promotion, given low grades, received inadequate pay rises, been fired, jilted [...] etc. commonly relate that they have been screwed, fucked (royally), diddled, butt-fucked, fucked over and so on.
[US]N. Stephenson Cryptonomicon 771: I have been out in the world [...] getting butt-fucked by Fortune.
[US]C. Hiaasen Sick Puppy 285: Customers who believed they’d been gypped, deceived, baited, switched or otherwise butt-fucked.
[US]C. Goffard Snitch Jacket 199: The economic butt-fucking of indigenous Eskimo populations.

3. (US) to injure.

[US](con. 1968) D.A. Dye Citadel (1989) 136: The grunts come panting in, carrying their asshole buddy who has just been butt-fucked by a B-40.