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you can get a fan that pulls smoke out your window, or you can use the strategy my friend used to use, you take two two-litre bottles, cut a small hole in one near the bottom (on the side), and cut the bottom off the other one. then take the one that has the bottom cut off, fill it somewhat loosely with toilet paper, and stick a drier sheet on the end. smoke your joint holding the tip in the one with the hole in the side, and then exhale through the mouth piece of the tp one.
also, a towel under the door is good, as is incense (if you use incense)