Green’s Dictionary of Slang

(drugs) marijuana.

1936		C.R. Cooper Here’s to Crime n.p.: Commonly it now being called ‘fu’, ‘mezz’, ‘mu’, ‘moocah’, ‘muggles’, ‘weed’ and ‘reefers’.
1938		D. Maurer ‘Lang. of the Und. Narcotic Addict’ Pt 2 in Lang. Und. (1981) 102/2: fu. 1. Marijuana, or cannabis indica.
1953		Anslinger & Tompkins Traffic In Narcotics 308: fu. Marihuana.
1959		J.E. Schmidt Narcotics Lingo and Lore.
1982		Abel Marihuana Dict.
2001		ONDCP Street Terms 9: Fu — Marijuana.