Green’s Dictionary of Slang

1. (also cough it) to confess, to inform.

1900		A.H. Lewis Sandburrs 81: Not one of ’em coughs on me, an’ me name ain’t never in it.
1907		W.M. Raine Bucky O’Connor (1910) 114: Cough it out, Mike.
1921		P. & T. Casey Gay-cat 62: Thet guy Blondy had coughed on me. He had got me trapped.
1975		‘P.B. Yuill’ Hazell and the Three-card Trick (1977) 146: ‘What you want from me.’ [...] ‘A confession. How you worked the oracle with Jennifer Carmichael. Just cough the lot, that’s all I want.’.
1980		J. McClure Spike Island (1981) 96: He’s not going to cough for the first half-hour, so I leave him in the cells for a bit.
1989		J. Morton Lowspeak.
2007		N. ‘Razor’ Smith Raiders 254: He coughed the lot about the hoover robberies.
2009		P. Temple Truth 72: He put the plug in his ear, found the place on the player. …listen, I’ve had a bloke, he’s offering … Coughing.
2013		K. Sampson Killing Pool 116: From the moment Kalan coughed about Misha things have gone from bad to worse.

2. to hand over, to give, esp. money.

1899–1900		C.L. Cullen Tales of the Ex-Tanks 256: I coughed a dollar for a seat.
1901		‘Hugh McHugh’ Down the Line 43: In the annals of the road no one could look back to the proud day when Sledgeheimer had coughed.
1908		K. McGaffey Sorrows of a Show Girl Ch. xi: Loosen up, cough, give down, come to, kick in. You’ve got to donate.
1941		A. Gurney Bluey & Curley 26 Apr. [synd. cartoon strip] You’ll cough that half quid....You cow.
1996		J. Cameron It Was An Accident 15: Housing Benefit out to cough most of that.