Green’s Dictionary of Slang

1. to inform, to tell tales, to betray; thus grassing n.

1929		Illus. Police News 29 Aug. 3/4: The officer said that Reid then asked, ‘Who’s been grassing?’ That meant, explained the officer, ‘Who has been informing about us?’.
1936		G. Greene Gun for Sale (1973) 182: She’s straight, he swore with almost perfect conviction, she wouldn’t grass.
1943		J. Phelan Letters from the Big House 28: He’ll be too fed up to go any real grassing.
1957		P. Beveridge Inside the C.I.D. 123: He ‘grassed’ (informed) on the gang, and another nine men went to gaol.
1961		(con. 1920s) J. Sparks Burglar to the Nobility 12: It is only those [...] who know nothing that can be truly relied upon not to grass.
1968		J. Barlow Burden of Proof 87: Danny had grassed. Betrayal was half expected in their world.
1973		Sun. Times Mag. 30 Sept. 38: I was inside 18 months. Burglary and I got grassed, by a white guy. He grassed me up.
1983		A. Payne ‘Willesden Suite’ Minder [TV script] 75: That Norma grassed him good and proper.
1984		B. Ellem Doing Time 190: grass: to inform; an informer.
1989		T. Blacker Fixx 197: The simple expedient of grassing her up to her husband.
1995		J. Cameron Vinnie Got Blown Away 146: Old-time cons never grass their worst enemy.
1996		(con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 83: ‘She probably thinks her little performance scared you too much to grass’.
1998		G. Burn Happy Like Murderers 353: If they went to the police, it would be like grassing her up.
2000		I. Rankin Set in Darkness 396: It wasn’t enough to grass me to the pigs.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 81/1: grass v. to inform upon, to tell upon, to give someone up to the police.
2004		Guardian 28 Aug. 7: I have never informed on anyone in my life, never grassed anyone up.
2006		D. Mitchell Black Swan Green 79: I didn’t grass you off when you made Nigel cry.
2009		T. Black Gutted 260: You want me to grass on my own? [...] I can’t do that.
2010		L. Redhead Thrill City [ebook] Don’t implicate the Devils [...] No one grasses, no one testifies.
2011		Independent 12 May 4/2: Tweeting, blogging, and otherwise grassing each other up.
2015		I. Welsh Decent Ride 49: Eh’s tryin tae work oot if it’s a guid idea tae grass some cunt up.
2017		L. McInerney Blood Miracles : ‘I’ve got [...] a couple of weeks before Dan finds out I’ve grassed him up’.
2018		G. Gilmore Class Act [ebook] ‘[I]f journalists started letting on about their grasses, no one would ever grass again’.
2020		G. Armstrong Young Team 9: ‘Somecunt in school wull grass yi fur name-drappin’.
2021		P Howard Braywatch 382: ‘Some wooden’s arthur grassing, Rosser’.
2024		J. Meades Empty Wigs (t/s) 323: He says I grassed him. I didn’t. What he means is that I refused to perjure myself.

2. (Aus.) to fool, to deceive.

1983

J. Byrell (con. 1959) Up the Cross 65: ‘Oh come on, Phyllis [...] Who’re you trying to grass? What about you and that baccarat dealer?’.