atom bomb, n. — Green’s Dictionary of Slang

atom bomb n.

[play on SE atomic bomb, intensified by bomb n. (8)]

(US drugs)

a combination of marijuana or hashish with opium or heroin.

1975		Hardy & Cull Drug Lang. and Lore.
1982		Abel Marihuana Dict.
2001		ONDCP Street Terms 2: Atom bomb — Marijuana mixed with heroin.