1 week detox, Saunas ,sweating exercise plenty of water vitimans(fruitjuice) if in despair maybe laxitives and water for a day or two or something.
Really there isnt a way to get it out of your blood so quick(blood transfusion) but to get rid of it enough to be able to say you were "passive smoking at a party" should be sufficient. deny all knowledge but a hippy friend whom you havent seen for years just turned up out the blue for a birthday or something thats the only possability of cannabis to be in your system, also if you choose to use someone elses then make sure they are not preegnant or youll be chased down by the men in white!
cheers.