Ghetto Preppy. Having a ghetto personality, and a preppy look. Or a preppy personality and a ghetto look. A preppy person gets straight A+, is super smart, and wears preppy brands. A ghetto person wears baggy sweatshirts and/or tight pants, is a slacker, and is a "cool kid". Greppy is an ah-mazing combination of the two.
Greppy girl, in pink skirt/Ralph Lauren blazer, "yo, sup. dudeeeee thts SICK."
Greppy girl, dressed in short shorts and ripped tank, "I must go practice my violin. After that I have lacrosse, SAT prep, studying for all my AP classes, reading the dictionary, tennis lessons, and preparing for my future profession of neurology."