It is gross to smoke old cigarette butts.
Marc just ran out of tobacco and is going through nicotine withdrawal.
Marc wants to enjoy a smoke.
Marc wants some tobacco now, so he hurries up to his car where he drives to the convenience store several blocks away.
Marc wants some tobacco now, so he goes in the ashtray and rolls up the butts he finds in a hemp paper.
Marc is able to satisfy his nicotine craving fast.
The taste is horrible and now Marc smells like an ashtray.