Swass is when you are riding on the subway in Boston and the aquariumdoors open. In comes a blouser weighing in at about 300 plus wearing the wife-beater shirt. He stands up in front of you holding the pole. All you can see and smell is SWASS.
When a girl with a nice ass walks in that special way... swaying back and forth its mezmorizing... Then add a little sass to the equasion and you have SWASS.