Stands for LA Face with an Oakland Booty: LAFOB ala Sir Mix-a-lot song "I Like Big Butts".
Refers to a girl with a pretty face and a marvelous shapely ass.
Guy 1: Did you see that girl with the pretty face?
Guy 2: Yeah and she had the best ass I've seen in a while!
Guy 1: Yeah, she's a Lafob fo' sho'