Green’s Dictionary of Slang

key n.2

also kee, keye, ki
[abbr. kilogram]

1. (drugs) one kilo of marijuana, hashish or any other drug.

[US]N. von Hoffman We are the People Our Parents Warned Us Against 37: Grass is available in five-hundred-kilogram lots [...] or ‘key’. [Ibid.] 171: I saw sixteen keys of grass under the bed.
[US]R.R. Lingeman Drugs from A to Z (1970) 135: key, also spelled ki. A kilogram (2.2 pounds) of a drug, especially a pressed block of marijuana of this weight.
[US]E.E. Landy Underground Dict. (1972) 114: kee [...] 2.2 pounds of marijuana.
[US]R. Woodley Dealer 10: [of cocaine][C]ocaine is sold cut in $10 or $20 capsules [...] teaspoons and tablespoons (tablespoons are ‘quarters’); ‘pieces,’ which are four tablespoons, or about an ounce; parts of ‘keys’ (kilograms, 2.2 pounds) from eighths, quarters, halves, all the way to whole keys of pure cocaine.
[UK]Thom Gunn ‘Street Song’ in Moly With Midday Mick man you can’t lose, / I’ll get you anything you need. / Keys lids acid and speed.
[US]V.E. Smith Jones Men 17: He gettin’ in some keyes, you know.
[US]R.D. Pharr Giveadamn Brown (1997) 177: ‘We need thirty keys of heroin for bait’.
[US]E. Folb Runnin’ Down Some Lines 170: Next time, I’ma get me a whole fuckin’ key.
[UK]V. Headley Yardie 12: Skeets seh is one ki you bring.
[US]T. Williams Crackhouse 74: Even the big-time coke man [...] even the one selling keys is selling cooked-up stuff more.
[US]UGK ‘Cocaine in the Back of the Ride’ 🎵 Sellin fifty dollar slabs as I’m slangin them ki’s.
[US]UGK ‘Hi Life’ 🎵 But I got one foot in the street / And every week I flip a Ki.
[US]W. Shaw Westsiders 11: A key is a kilo of cocaine.
[US]J. Lethem Fortress of Solitude 362: He and I and Mathew had spent the waning hours of that first afternoon divvying Arthur’s quarter kee into Camden-sized portions.
[US]T.I. ‘Long Live Da Game’ 🎵 Grab my scale / Get another ki and I'mma slang my yayo.
[UK]K. Sampson Killing Pool 59: Getting the gear [i.e. cocaine] in, getting it cut and getting it back out to the network, the ten-key men, the five-key men, right down to the little street teams.
[US]D. Winslow The Force [ebook] ‘A dope case, a quarter key of coke’.
[Ire]Breen & Conlon Hitmen 221: ‘I made a good bit [...] on five keys [i.e. of crack cocaine]’.
[US]C. Stella Joey Piss Pot 233: ‘A key of cocaine isn’t remotely funny. Technically more than a key’.

2. £1000.

[UK]J.J. Connolly Layer Cake 159: Would Jimmy give him two key in readies on the old man’s behalf?