Green’s Dictionary of Slang

tip off v.²

1. to warn.

1895		E. Townsend Chimmie Fadden Explains 32: I seen him wink at de mug and tip me off like he was tellin him for t’ hold his mout in front of me.
1901		‘Hugh McHugh’ Down the Line 51: I [...] quietly tipped Bud off to the fact that it will be a case of wedding bells when Willie gets a wad — be nice! be nice!
1910		Committee of Fourteen Social Evil in N.Y. City 49: The policemen in uniform went just ahead of the detectives and ‘tipped off’ the proprietors of these places as to the time when the women could safely emerge.
1920		R. Lardner Big Town 186: What was the sense of me tipping off a guy that had said them sweet things about I and Ella?
1930		J. Lait Put on the Spot 26: If youse two can croak him an’ not be tipped off, okay; if youse can’t, do it anyways.
1933		C. Drew ‘Gorilla Grogan’ in Bulletin (Sydney) 26 July 40/4: I’d tipped Snatcher off to spill it round that Gorilla had been saying things about Staggs and it was to be a grudge fight.
1937		R. Westerby Wide Boys Never Work (1938) 28: I was only tipping you off for your health’s sake, kid.
1943		(con. 1850–60s) G.A. Little Malachi Horan Remembers 25: Steeven’s Hospital [...] used to pay a man to watch the burial ground at Saggart to tip them off when he saw a chance.
1954		Mad mag. June 9: This is a frame, see! Nyaah! I tipped the cops off to this caper!
1964		Larner & Tefferteller Addict in the Street (1966) 132: I was hiding in the basement, and somebody tip off the police.
1971		R.D. Pharr S.R.O. (1998) 30: ‘The bastid risks his neck [...] to tip off the dope peddlers when the fuzz xomes to call’.
1992		in R. Graef Living Dangerously 206: They tip them off before the raids.
2000		J. Hawes Dead Long Enough 304: Luckily for us his wife [...] tipped us off.

2. to provide with information.

1896		F. Hutcheson Barkeep Stories 11: ‘An’ I’ll tip annuder t’ing off t’ youse guys — I’ll not take no steers from dat Muggins no more!’.
1901		J. Flynt World of Graft 39: For this remuneration I should expect that he would refrain from tipping me off to his superiors.
1913		B.T. Harvey ‘Word-List From The Northwest’ in DN IV:i 28: tip off, v. To inform about.
1916		J. Lait ‘If a Party Meet a Party’ in Beef, Iron and Wine 1917 101: ‘Arthur,’ she said to him, ‘tip this fresh harness bull off to what you think he oughta get wise to before they make kindlin’ wood outta his hickory.’.
1928		M.C. Sharpe Chicago May (1929) 5: The police would not bother me much if it were not for stool-pigeons tipping them off and lying about me.
1935		C.G. Finney Circus of Dr Lao 89: The doc tipped me off to something hot.
1946		Mezzrow & Wolfe Really the Blues 133: I tipped her off as to how we were bigtime musicians from Chicago.
1953		J. Thompson Savage Night (1991) 12: I must have tipped you off.
1965		R.L. Pike Mute Witness (1997) 173: Who tipped you off in the first place?
1972		P. Fordham Inside the Und. 76: A crooked cooper [...] who actually tipped him off.
1989		Pileggi & Scorsese Goodfellas [film script] 23: They tipped us off about what was coming in.
1999		K. Sampson Powder 66: What we’ll do [...] is tip off Chris Cowie way up front. Take ourselves out of the reckoning, but involve Cowie in the proces, yeah?
2000		Indep. Rev. 9 Feb. 4: They were suddenly surrounded by a large number of policemen, tipped off by the anxious newsagent.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 190/1: tip off v. to inform upon.
2023		(con. 1962) J. Ellroy Enchanters 7: Fox kingpin Darryl Zanuck got tipped off.

3. to expose someone.

1915		G. Bronson-Howard God’s Man 363: Don’t you try to convince anybody you’re one of the wise ones. Because your map tips you off ...
1928		J. Callahan Man’s Grim Justice 262: Don’t worry, Jack [...] I’ll not tip y’ off. I’ll never say a word.

In derivatives

tipped (adj.)

(N.Z. prison) aware, informed.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 190/1: tipped adj. awake, aware, informed.

In phrases