Green’s Dictionary of Slang

sure thing n.

(US) an absolute certainty, a guarantee.

1809		Horry & Weems Life of General F. Marion (1816) 168: Oh no, massa! dey burn de barn, dat sure ting!
1836		J. Hildreth Dragoon Campaigns in Rocky Mountains 24: I say, stranger, didn’t I say that old ‘Slow and Easy’ was a sure thing, in the end?
1859		C. Abbey diary 1 Aug. in Gosnell Before the Mast (1989) 236: I have a bet with him [...] Guess I’ve got a ‘sure thing’ on him too.
1865		Leaves from Diary of Celebrated Burglar 45/2: ‘And you say you [...] saw them go into the theatre?’ asked Joe. ‘Yes, that’s a sure thing, for I never took my eyes off them.’.
1873		J.H. Beadle Undeveloped West 140: I had the pleasure (?) of seeing at least a score of ‘smart Alecks’ relieved of their surplus cash by betting on the ‘strap game,’ [...] and other beautiful uncertainties which are so worked as to appear ‘a dead sure thing’ to the uninitiated.
1887		G. Devol Forty Years a Gambler 36: My Jew partner [...] was so delighted with the sure thing of having won.
1894		Mirror of Life 18 Aug. 2/3: The race course boys who would give us [...] a sure thing.
1896		J.F. Lillard Poker Stories 52: He was working George on a dead sure thing.
1897		Capricornian (Rockhampton) 6 Feb. 30/4: I never let my moke go unless I’ve got a pretty sure thing on.
1903		H. Hapgood Autobiog. of a Thief 80: The latter were too eager to make money on a sure-thing.
1914		Joyce ‘Ivy Day in the Committee Room’ Dubliners (1956) 127: I got him one or two sure things in Dawson Street, Crofton and myself.
1918		V. Marshall Jail From Within (1969) 22: The ‘sure thing’ had been ‘pipped on the post’.
1926		E. Walrond Tropic Death (1972) 173: Dem n’ah go – dat a sure t’ing!
1928		M.C. Sharpe Chicago May (1929) 37: There was a saloon downstairs and a pool-room upstairs, with the fake wires for the suckers looking for a sure thing.
1929		C. Coe Hooch! 80: It’s a sure shot, Boss.
1931		D. Runyon ‘The Old Doll’s House’ Runyon on Broadway (1954) 69: It is a sure thing that Lance will be very severely punished.
1933		‘Goat’ Laven Rough Stuff 37: I’m playing a sure thing now, the short money racket.
1934		(con. 1920s) J.T. Farrell Young Manhood in Studs Lonigan , (1936) 318: The next time you boys want a ‘sure’, let me take you there.
1935		G. Ingram Cockney Cavalcade 241: He ain’t mine, that’s a sure model!
1939		K. Tennant Foveaux 31: I’ve an idea that if we back Twofold for a place on Saturday, we’re on a sure thing.
1940		D. Maurer Big Con 2: Dealings which are explained to him as being dishonest — and hence a ‘sure thing’.
1957		H. Simmons Corner Boy 14: Everybody wanted to get in on a sure thing.
1965		C. Brown Manchild in the Promised Land (1969) 169: Around the first of the month it [i.e. the Murphy (Game), the n.] was a sure thing.
1980		(con. 1940s–60s) H. Huncke ‘Detroit Redhead’ in Eve. Sun Turned Crimson (1998) 113: Ricci had said, ‘This is a sure thing’ — as per result they were overly confident and that was it.
1992		S.L. Hills Tragic Magic 69: I always liked to play the sure shot.
1999		K. Sampson Powder 110: A gambler with a sure thing scrawled on a ciggie packet.
2000		G.V. Higgins At End of Day (2001) 141: I dropped out on four sure things, and everyone went in on them made a whole shitload of money.
2013		T. Peacock More You Bet 6: A ‘good thing’ might also have been referred to as a ‘sure thing,’ or a ‘certain cop,’ or a ‘sure cop,’ or a ‘dead bird’ or a ‘dead cert’.

In derivatives

surethinger (n.)

one who only bets on a lit. or fig. favourite.

1913–14

Van Loan ‘No Business’ Taking the Count 158: How these surethingers do climb aboard when they think they’ve got a cinch.