B, n.³ — Green’s Dictionary of Slang

B n.³

also bee

[abbr. SE box]

(drugs) enough marijuana to fill a matchbox.

1969		R.R. Lingeman Drugs from A to Z (1970) 43: bee [...] box or bag of marijuana.
1971		E.E. Landy Underground Dict. (1972).
2001		ONDCP Street Terms 2: B — Amount of marijuana to fill a matchbox.