Green’s Dictionary of Slang

(US drugs/prison) narcotics smuggled into jail.

1936		D. Maurer ‘Argot of the Und. Narcotic Addict’ Pt 1 in AS XI:2 127/1: trained nurse. Narcotics smuggled into jail with an addict to ‘take care of him’ while he is there.
1959		J.E. Schmidt Narcotics Lingo and Lore.