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The rule that states that if an individual has left an item at a friend's house that hasn't been moved or used within a 3 week period: then that item may be used by the household's occupants as an improvised ashtray.
Nathan: "Dude I was gonna make a coffee why the shit is my coffee mug full of ash and cigarette ends?"

Billy: "3 week rule man you have plenty of time you move it or use it"

Nathan: "I was in hospital I was in a fucking car crash you dick!"
by Hamster_Jelly February 10, 2017
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