I have a diesel furnace, where the exhaust goes there is a pipe with a circular flap. All I have to do is weigh the flap down with a bolt or screw driver, smoke next to the flap and all the smoke is sucked up and out.

Tip for smoking out a window, it is best to open both top and bottom so as to allow circulation. Usually you'll want to blow the smoke out the top since heat rises but it may depend on the room temperature and outside.