Green’s Dictionary of Slang

1. (US drugs) a cocaine user.

1918		Jackson Dly News (MS) 1 Apr. 7/3: Crook Chatter [...] ‘One addicted to the use of drugs is either a “snowbird,” “cokomo” or “hop-head”’.
1938		D. Maurer ‘Lang. of the Und. Narcotic Addict’ Pt 2 in Lang. Und. (1981) 101/1: cokomo or kokomo. A cocaine addict.
1949		Monteleone Criminal Sl. (rev. edn) 54: cokomo A cocaine user.
1953		Anslinger & Tompkins Traffic In Narcotics 311: kokomo. A drug addict, especially a cocaine addict.
1959		J.E. Schmidt Narcotics Lingo and Lore 33: Cokomo – A drug addict whose chief inquisitor is the alkaloid of E. Coca. [Ibid.] 98: Kokomo [...] Kokomo Joe – Not a Hoosier from Kokomo, but a fugitive from reality with the aid of nepenthean cocaine.
1971		E.E. Landy Underground Dict. (1972).

2. (drugs) crack cocaine.

2001

ONDCP Street Terms 13: Kokomo — Crack Cocaine.