Green’s Dictionary of Slang

1. (also toss) a wager (esp. fig.) in which chances are even and either eventuality is equally likely [SE toss up coins].

1772		G. Stevens ‘The Toper’ in Songs Comic and Satyrical 73: Life and Death at a stand, / A toss-up which party will take us.
1800		M. Edgeworth Castle Rackrent (1832) 39: It’s a toss up with me which I should marry this minute, her or Mr. Moneygawl of Mount Juliet’s town’s daughter.
1809		B.H. Malkin (trans.) Adventures of Gil Blas (1822) IV 216: It is a toss up who fails and who succeeds: the wit of to-day is the blockhead of tomorrow.
1857		T. Hughes Tom Brown’s School-Days (1896) 166: It was a toss-up whether they turned out well or ill.
1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor I 482/1: I has a toss up sometimes when I has a odd copper for it.
1871		C. Money Knocking About in N.Z. 123: It was a toss-up for his life; but he was let off eventually with a fearful ‘hiding.’.
1888		R. Barnett Police Sergeant C 21 87: He and I were so evenly matched that it was always a toss up who should win.
1899		C.J.C. Hyne Adventures of Captain Kettle 283: It was quite a toss-up even then.
1901		Boy’s Own Paper 27 Apr. 468: It was a ‘toss up,’ as regards distance, whether to the right or left.
1910		H.G. Wells Hist. of Mr Polly (1946) 125: It’s a toss up. The hotter come, the sooner cold.
1922		Wodehouse Clicking of Cuthbert 129: It is always a toss-up which of us wins.
1926		Wood & Goddard Dict. Amer. Sl. 57: toss or toss up. An even chance.
1947		S. Carnegie Snow in Lehmann Penguin New Writing No. 30 188: It was a toss up: go straight back to the company or make a detour down the hill.
1958		A. Sillitoe Sat. Night and Sun. Morning 7: Having won the toss-up for choice, he led off on gins.
1967		W. Murray Sweet Ride 191: It’s still a toss-up on what they’re going to do.
1979		F. Norman Too Many Crooks Spoil the Caper 105: It’s a toss-up who duffs me first – the law or the hounds.
1986		F. Taylor Auf Wiedersehen Pet Two 175: Mind you, it’s a toss-up as to who’d give me a harder time.
1999		Indep. Rev. 2 July 15: It’s a toss-up whether mankind is the richer for their perseverance. Probably not.
2000		Guardian 28 Jan. 32: Favourite drink: Toss-up between Indonesian lager top with a vodka and Red Bull chaser, or Southern Comfort and Irn Bru.
2010		K. Richards Life 371: Ronnie [Wood] wasn’t necessarily a shoo-in as our new guitarist [...] and it was really a toss-up.

2. (drugs) a woman who trades sex for crack cocaine or for money to buy crack cocaine.

2001

ONDCP Street Terms 21: Toss up — Crack Cocaine; female who trades sex for crack or money to buy crack.

3. (Aus.) gang sex, voluntary or coerced.

1985

‘Thommo’ Dict. Aus. Swearing & Sex Sayings 131: TOSS UP — Chop up, mob job or gang bang.

4. (Aus.) a promiscuous woman; also attrib. [SE toss, to throw; she throws herself ‘up to’ the man].

1993		M.B. ‘Chopper’ Read How to Shoot Friends 117: I’ve seen a truckload of so-called strippers, most of them gang bang toss-ups pretending to be Gypsy Rose Lee.
2005		M.B. ‘Chopper’ Read Chopper 4 76: From what I’ve seen, half the toss up molls in Australia live in Tassie.