Green’s Dictionary of Slang

(US drugs) to smoke marijuana in an enclosed space.

1997–2002		Hope College ‘Dict. of New Terms’ 🌐 clam baking v. intrans. Burning and inhaling of marijuana openly in an enclosed area with multiple people [...] ‘They’re clam baking in the tent.’.
2002		The Danktuary Marijuana Dict. 🌐 Clambake [n.] A pot smoking session that takes place in a small, closed, confined space so that the smokers may increase their high by breathing secondhand smoke; a hotboxing session.