Embrace offers very nice advice. Wish I had his guide when I was in college.

If someone is living in a suite-type dorm, then they should try smoking in the bathroom. Back at college, the bathroom was in the center of a cluster of dorm rooms and therefore had no windows. Instead, it had air-intake vents in the ceiling. Just smoke in a stall and blow into these vents. The smoke is taken up and away, and never has the chance to drift into the halls because of the way the air flows.

Again, this only works with semi-private baths.