Green’s Dictionary of Slang

1. to shoot with a pistol or revolver.

1812		Vaux Vocab. of the Flash Lang.
1834		(con. 1737–9) W.H. Ainsworth Rookwood (1857) 263: Flip him, Dick, fire, or I’m taken.
1859, 1860		Hotten Dict. of Modern Sl. etc.
1890		Bulletin (Sydney) 16 Aug. 24/4: Look ’ere – missie, yer did – th’ kin’est thin’ – pos’ble – in joggin’ – that lobster’s elbow – an’ makin’ him flip his gun.
1935		R.T. Hopkins Life and Death at the Old Bailey 63: The following crook’s words and phrases date from the days of the old Old Bailey: [...] to shoot a man – to flip.

2. (US) to steal a ride, esp. on a freight train, thus n. flipping, riding for free.

1916		J. Lait ‘Omaha Slim’ in Beef, Iron and Wine (1917) 110: He heard a noise, looked up, and saw the train that he was going to flip pulling out.
1926		N. Klein ‘Hobo Lingo’ in AS I:12 651: Flipping—train riding.
1927		F.M. Thrasher Gang 121: We used to flip the freights [...] but we got caught at Waukegan and were sent home.
1930		(con. 1890) G. Milburn ‘A Convention Song’ in Hobo’s Hornbook 27: Some flipped freights to other states.
1937		‘Boxcar Bertha’ Sister of the Road (1975) 182: They all started telling their stories of flipping freights and hitch-hiking.
1949		Monteleone Criminal Sl. (rev. edn).
1962		Ragen & Finston World’s Toughest Prison 799: flip – To board a moving train.
1965		H. Williamson Hustler 42: [of streetcars] [W]e didn’t have no car, we’d go on the ‘L’—flip the ‘L,’ and come back.
2006		www.landmarktouring.com 🌐 Learn how to ‘flip a freight’, how to read the signs the hobos left for fellow travelers, their code of ethics, unique monikers, slang and art.

3. (US drugs) to make another addict unconscious in order to steal their drugs.

1936		D. Maurer ‘Argot of the Und. Narcotic Addict’ Pt 1 in AS XI:2 121/: flipped. Knocked out by some kind of knock-out shot administered by an attendant or by another addict who then makes his victim for any narcotics he may have.
1949		Monteleone Criminal Sl. (rev. edn).

4. (US black) to reject someone.

1947

M.H. Boulware Jive and Sl. n.p.: Flip the chick ... Quit the girl.