Green’s Dictionary of Slang

1. a cache of drugs.

1933

D. Maurer ‘Junker Lingo’ in AS VIII:2 27: The rations—usually sold at a standard price of $1.00—are designated, according to the type of drug involved, as checks, bindles, or O.Z.’s.

2. (drugs) a dose or injection of drugs.

1936		D. Maurer ‘Argot of the Und. Narcotic Addict’ Pt 1 in AS XI:2 125/2: ration. A shot of dope [...] The size of the ration varies with the type of dope, the length of time the addict has been using it, and the tolerance he has built up.
1949		Monteleone Criminal Sl. (rev. edn).
1955		H. Braddy ‘Narcotic Argot Along the Mexican Border’ in AS XXX:2 85: RATION, n. A shot of dope.

3. (N.Z./US) sexual entitlement, thus draw rations, to have sex.

1939		Honolulu Star-Bulletin (HI) 25 Mar. 33/1: ‘Drawing rations’ has nothing to do with being issued foodstuffs [...] it pertains to ‘making love — in Brooklyn!’.
2003		McGill Reed Dict. of N.Z. Sl.