Alright, this is kind of odd but it's really bothering me so I have to know. My roommate continually smokes hookah and I can't figure out for the life of me why when he sucks on the hose, air comes OUT and bubbles into the water. (1) Conservation of mass? Where's the extra air coming from? (2) How is the extra air's direction being reversed? To me, sucking on the hose would act just like a straw and water would go up into the mouth but it doesn't. Oh, and blowing into the hose causes the piece submerged in water to act as a suction device. Anyone familiar with how this works?