A word used by white suburban kids who think they are gangster to describe something "cool"/stupid and used to describe how "gangsta"/gaudy their wigger friend's ricer is.
1. A word to describe a rhythm that one likes. Comes from back in the old days, when people would call certain beats in songs "fat," referring to their presance. It's been adopted into slang rather recently, probably in the late 80s.
2. Often made into the backronym of "pretty hot and tempting." This is not what it originally stood for, but things change.