Green’s Dictionary of Slang

1. (UK Und.) to carry out a successful crime.

1865		Leaves from Diary of Celebrated Burglar 51/2: My ‘moll,’ for one, ‘got it off’ last night, and she was looking for me to ‘sling’ the ‘sugar’ to me. [Ibid.] 106/2: I’se think thau’s bin’ ’avin ’t off’ laitely, by t’ looiks o’ things — ‘sparks’ i’ th’ breast; ‘sparks’ i’ th’ ‘duke’.
1930		(con. 1910s) D. Mackenzie Hell’s Kitchen 86: I recall once when a mob had ‘had it off’ (done a job and been paid so that they were in funds).
1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 5: Have it off: Commit crime.
1937		J. Curtis You’re in the Racket, Too 61: It’s a cinch, we’ll have it off sweet as a nut.
1956		‘Charles Raven’ Und. Nights 24: If a crooked person was nicked every time he or she had it off, H.M. Prison Commissioners would have to build at least twenty new nicks.
1961		T. Taylor Baron’s Court All Change (2011) 124: [of drug dealing] The only places that you could have it off with the little brown packets were a couple of shady clubs.
1962		F. Norman Guntz 63: A geezer goes out and has it off for a nice little tickle.
1970		G.F. Newman Sir, You Bastard 72: God strike me dead I didn’t have it off.
1974		G.F. Newman You Flash Bastard 38: ‘Bernard Hart? What d’you hear about him?’ There was a chance he might have known him. But didn’t. ‘Have a quiet punt around, he might be having something off. Some tom.’.
1989		in G. Tremlett Little Legs 39: Did you have it off?
2001		K. Sampson Outlaws (ms.) 4: The Garden Festival sent these hordes of tourists and trippers right into our own back yard [...] expressly to be had off. By us. [Ibid.] 32: This cunt behind, one of the most ruthless cut-throats in North Liverpool, is going to try and have our gear off.

2. to be successful in any area, but in a specific task.

1897		Truth (London) 10 June 35/1: ‘Lor! ’ow that ’at was tipped! You or I might ’ve practised it for a year and never ’ave it orf’.
1937		J. Curtis There Ain’t No Justice 34: I’m glad you won. I’ll be here to watch you next week. I hope you have it off again.

3. (UK Und.) of police, to make a successful raid and arrest.

1956

J. Curtis Look Long Upon a Monkey 190: Because you ain’t had it off, you’re going to take it out of my body.