Green’s Dictionary of Slang

1. (orig. US) a bloody fool.

1894		F.W. Benteen in Benteen-Goldin Letters 6 July (1991) 223: Besides being a ‘C.P.’ he was a ‘B.F.’ of first water.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 12: B.F. [...] Ordinary contemptuous slang: e.g., ‘He’s an out and out B.F.!’.
1933		E. Blair letter Mar. in Complete Works X (1998) 307: Don’t read ‘James Joyce for the Plain Reader’ by some BF called Duff — it is about the worst piece of criticism I have yet read.
1938		Eve. Post (Wellington, NZ) 27 Oct. 24/1: He had found padres divided into two classes, ‘Damned good sports’ or ‘BFs’’.
1940		S. Lister Mistral Hotel (1951) 47: It looks as though I have made a B.F. of myself!
1944		M. Morrison letter in Blake Morrison Things My Mother Never Told Me (2002) 186: Don’t be a BF. You’re ideally suited.
1959		A. Sinclair Breaking of Bumbo (1961) 121: Don’t be a B.F. I’m a friend of Jock’s.

2. (US campus) a boy friend.

1925		R. Lardner ‘Zone of Quiet’ in Coll. Short Stories (1941) 66: I’m going with my G.F. Her B.F. gave her the tickets and he’s going to meet us after the show.
1932		J.L. Kuethe ‘Johns Hopkins Jargon’ in AS VII:5 329: b.f.—boy friend.
1939		W. Winchell On Broadway 17 June [synd. col.] Sonja Henie’s real b-f isn’t any of the fellows whose names have been blended with hers in the columns.
1944		E. Wilson 11 Dec. [synd. col.] David P. Lewis [...] one of her [i.e. Joan Fontaine] many B.F.’s .
1999		Ellie Somethingnormal.com 🌐 Amy asks me about Jerkhead (the exBF) ... and I proceed to give a very brief rundown. The 40 year old, obviously eavesdropping, chimes in ‘good for you’ when I say I broke up with Jerkhead in March.
2002		‘Little Donald’ Wetville.net 14 Jul. 🌐 Ruffy pulls the bf on to her as her crotch issues forth with a flood, soaking both bed and bf... she squirms as hot as a firecracker, squeesing and peeing, soaking and wetting, and the bfs pants are wet now too.

3. (US Und.) a pimp.

1939

D. Maurer ‘Prostitutes and Criminal Argots’ in Lang. Und. (1981) 116/1: b.f. A pimp.

4. (US gay) in a lesbian couple, the ‘male’.

1972

B. Rodgers Queens’ Vernacular 31: BF (les sl, mid ’60s, acronym for boy friend) the lesbian who assumes the male role in a partnership romance.

5. (US campus) best friend.

1998

Eble Campus Sl. Apr. 1: b.f. – best friend. Often used sarcastically: ‘The nerd who sits next to me in chemistry wouldn’t stop talking to me. We are so BF.’.