Green’s Dictionary of Slang

Cadillac n.

[the perceived characteristic of the expensive marque]

1. (US) in drug uses.

(a) a 28g (1oz) packet of a powdered drug.

[US]J.L. Kuethe ‘Prison Parlance’ in AS IX:1 26: cadillac. An ounce of dope.
[US]Howsley Argot: Dict. of Und. Sl.
[US]Goldin et al. DAUL 39/1: Cadillac. A one-ounce package of any of the white powdered drugs.
[US]Wentworth & Flexner DAS.
[UK]J. Morton Lowspeak 34: Cadillac – an ounce of heroin, or, less usually, cocaine.
[US]ONDCP Street Terms 5: Cad/Cadillac — 1 ounce.

(b) any powdered, thus usu. narcotic, drug.

[US]Anslinger & Tompkins Traffic In Narcotics 306: a Cadillac. Cocaine.
[US]J.E. Schmidt Narcotics Lingo and Lore 24: Cadillac – A dose of a narcotic enough for one binge. Cadillac – A top quality narcotic.
[US]ONDCP Street Terms 5: Cadillac — Cocaine.

(c) phencyclidine.

[US]L. Young et al. Recreational Drugs.
[US]H. Feldman et al. Angel Dust 124: The large number of street names it has been accorded over the years: [...] cadillac.
[US]D.E. Miller Bk of Jargon 337: Cadillac: PCP.
[US]ONDCP Street Terms 5: Cadillac — PCP.

2. (US) in prison uses.

(a) coffee with cream and sugar.

[US]‘Jennifer Blowdryer’ Modern English 57: cadillac (n): Coffee with cream and lots of sugar. Helps prolong heroin high.
[US]Other Side of the Wall: Prisoner’s Dict. July [Internet] Cadillac: (1) Coffee with cream & sugar, smooth, rich and creamy.

(b) (also car) a line used for transferring articles, e.g. a pack of cigarettes, from one cell to another.

[US]Bentley & Corbett Prison Sl. 14: Car also Cadillac In ‘lockup’ units [...] inmates devise ingenious methods for passing cigarettes and other items from cell to cell. One of the most popular ways is to make a car or cadillac. A car is made by tearing bed sheets into long, narrow strips approximately three inches in width. These sheet strips are then tied to one another making one long strip. On one end is tied a paperback book which is actually referred to as the car. The book or car is then thrown to other cells, the item needed is tied to the book and the car is retrieved by pulling in the sheet strip.
[US]J. Lerner You Got Nothing Coming 76: Kansas makes a slipknot in the string, then takes a few test swings [...] before flinging the soap in a tight arc under the door. A second later Big Bear [...] has the soap/slipknot end of the Cadillac while Kansas still holds on to his end of the string.

(c) an easy job within the prison.

[US]Other Side of the Wall: Prisoner’s Dict. July [Internet] Cadillac: [...] (3) A cushion job on the inside.

(d) (also Cadillacker) something considered the best.

[US]Other Side of the Wall: Prisoner’s Dict. July [Internet] Cadillac: [...] (4) The best.
[US]UGK ‘Gravy’ [lyrics] I fuck the snow but I love a pro like flatbackers I’m a Cadillac’er.

(e) a vacant cell.

[US]Other Side of the Wall: Prisoner’s Dict. July [Internet] Cadillac: [...] (5) An officer’s term for a vacant cell.

SE in slang uses

In compounds

Cadillac commie (n.) [the Cadillac is trad. antipathetic to left-wing ideology]

(US) a liberal, the intensity of whose pronouncements on social problems is in direct proportion to their ability to escape their existence.

[US]Maledicta Monitor [Internet] Cadillac Commie one who hypocritically supports Communism and Marxism and mouthes their theories but who lives like a capitalist. Recent synonym for limousine liberal.
dispatches.phoblacht.net [Internet] Nicky’s now a wealthy Cadillac commie and an independent councillor in Wicklow.