Green’s Dictionary of Slang

(a) (US) to ‘come out’ as a homosexual.

1963

J. Rechy City of Night 109: Before I flipped [...] I was very Innocent.

(b) (US gay) to reverse one’s primary sexual activity, i.e. for a masculine lesbian to turn ‘femme’ or a sadist to play masochist; thus flippy adj., describing a homosexual who will take the active or passive role in intercourse.

1972		B. Rodgers Queens’ Vernacular 32: bisexual [...] flippy (also used of a homosexual who is able to fuck or be fucked).
1998		R. Scott Rebecca’s Dict. of Queer Sl. 🌐 flipping — to cause a stone butch to ‘melt’ or allow herself to be touched sexually, or to cause a top to bottom.

(c) (US) to convert a heterosexual to homosexuality.

1994		N. McCall Makes Me Wanna Holler (1995) 195: That guy was even more of a man if he could ‘flip’ another man, turn him into a homosexual.
2004		N. Kelley ‘The Code’ in Brooklyn Noir 185: These young ghetto bucks were obsessed with homosexuals [...] She could always tell which ones could be flipped.

(a) (US Und., also flip on) to inform (against); thus flipping, informing.

1960		C. Cooper Jr Scene (1996) 9: I won’t flip on you. I’ll never flip on nobody again.
1981		Maledicta V:1+2 (Summer + Winter) 264: The snitch goes up to a guard and he drops a dime, flips or turns over on a fellow inmate.
1995		L. Stavsky et al. A2Z.
2002		C. Stella Jimmy Bench-Press 127: He hasn’t flipped in the past because he wasn’t looking at enough time. This flipping thing works because of the network these guys establish.
2003		G. Pelecanos Soul Circus 208: ‘He’s the big Magilla in his corner of the world.’ ‘So nobody’s gonna flip on his brother.’.
2006		Burns & Zorzi ‘Unto Others’ Wire ser. 4 ep. 7 [TV script] Even if he flips on me, I ain’t gonna do shit to the man.
2012		‘Dutch’ ? (Pronounced Que) [ebook] You tryin’ to say my man might be flippin’?
2012		L. Berney Whiplash River [ebook] [H]e’d never flip on the Armenians.
2019		D. Winslow Border [ebook] ‘But, if you want, I pop you and then I put it out on the street you flipped. Not good’ [Ibid.] Then he went with Diego Tapia. Flipped on him when it was a matter of saving his own skin.
2020		D. Winslow ‘Crime 101’ in Broken 83: Has he flipped on me?

(b) to make someone into an informer.

1985		N. Pileggi Wiseguy (2001) 217: If there was ever a time to flip him against his old crew it was at that moment.
1996		(con. 1970s) J. Lardner Crusader 236: McCarthy had his detectives making buys for $25,000 and more, and then flipping the people they arrested in order to go after still-bigger operators.
2002		C. Stella Jimmy Bench-Press 127: We’d like to flip Larry Berra [...] but we’ll take whomever we can get.
2004		Mad mag. Nov. 25: You get busted for skipping detention, and the next thing you know, an FBI agent is trying to ‘flip’ you.
2012		C. Stella Rough Riders 96: You about to flip those investment bankers anyhow, the ones you nailed in that little sting.
2012		C. Stella Rough Riders 168: ‘Flipped?’ ‘Sorry [...] I’m talking a different language here. Flipped means they made a deal [...] Turned rat’.
2017		D. Winslow The Force [ebook] ‘Try to flip him? Get him to wear a wire?’.

(c) to tell a story.

1998

Source Oct. 88: You’re flippin’ stories in almost every track on your album.

(d) to turn state’s evidence.

2000

G.V. Higgins At End of Day (2001) 152: He’s the one that made Bernie flip and Bernie gave him me.