Green’s Dictionary of Slang

1. (drugs) marijuana.

1959		Esquire Nov. 70H: boo: marijuana.
1967		N.Y. Times 28 Feb. 39: Is the traditional boola-boola of Yale being replaced by plain boo, which translated from the underground argot, means marijuana?
1970		A. Young Snakes (1971) 33: I [...] smoked me some boo.
1976		R. Price Blood Brothers 149: She lays this dynamite boo on me, I mean super shit.
1988		D. Woodrell Muscle for the Wing 113: A smoking stick of boo was in her left hand.
2008		in S. Davis (ed) Land of the Permanent Wave ix: We began drinking and inhaling Mexican Boo Smoke almost before exchanging howdies.
2013		K. Shea ‘Having Chiqui’ in ThugLit July-Aug. [ebook] ‘Her and her pack of skanky bitches scamming free boo’.

2. attrib. use of sense 1.

2006

F.X. Toole Pound for Pound 219: Redwoods and sinsemilla, side by side in the boo capital of California.

3. methamphetamine.

2001

ONDCP Street Terms 4: Boo — [...] methamphetamine.