1. The instance of the anus (or ass) achieving a vacuum effect. In outer space, it is the black hole; in humans, it is the anus. It is the moment usually after a fart is expelled, the ass inhales air-- thus creating a vacuum effect. With practice, one can continue farting for minutes at a time through circular breathing (inhaling and exhaling) through the anus; best achieved while bent over on all fours, and relaxed. One may find extreme discomfort while the ass vacuum effect occurs while swimming.
2. A phrase used to express a moment of disappointment or even happiness by abrupt exclamation. Commonly used with a short, inward slurping sound made by the mouth, following the phrase to declare and enhance random/nastiness.
3. A statement similar to that of "EUREKA!" or of the same nature as having an epiphany or great idea; one could say "ass vacuum" in a very calm tone of voice or even a subtle whisper said near friends or strangers to cause them confusion or be interested in what you have to say.
4. A mediocre but effective derogatory name used against opponents or friends with whom you are currently disgusted with.
2. Dude... that teacher is such an ass vacuum.
3. "Ass vacuum..." in online chat.
4. Ok guys, time for the 2nd annual Ass Vacuum competition!