Green’s Dictionary of Slang

blow one’s roof v.

also blow one’s top
[blow v.1 (3b) + SE roof/roof n. (2)/top n. (3)]

(drugs) to smoke cannabis.

[US]Goldin et al. DAUL 30/2: Blow one’s roof or top. 1. To smoke marijuana.
[US]Anslinger & Tompkins Traffic In Narcotics 306: blow one’s roof. To smoke marihuana.
[US]Bentley & Corbett Prison Sl. 73: Smoke One Smoking a marijuana cigarette […] (Archaic: blow one’s roof).
[US]ONDCP Street Terms 3: Blow one’s roof — To smoke marijuana.