Green’s Dictionary of Slang

canoe v.2

[the burned side presumably resembles the hollowed portion of a canoe]

of a cigarette or cannabis cigarette, to burn down on top or one side rather than evenly.

[US](con. 1982–6) T. Williams Cocaine Kids (1990) 86: Masterrap, puffing on a cocaine-laced cigarette, complains to Charlie, ‘Hey, it’s canoeing’.