Reason to love Wikipedia #1,384,956:
"The slang term "bogarting", named after actor Humphrey Bogart, refers to taking an unduly long time with a cigarette, drink, etc., that is supposed to be shared (e.g., "Don't bogart that joint!"). It derives from Bogart's signature style of cigarette smoking, with which he left his cigarette dangling from his mouth rather than withdrawing it between puffs. Other terms to describe someone taking too long on a joint/blunt is called "babysitting", or "camping". http://bit.ly/oXhr9H
Even sourced, and sourced well.