This stands for "WP", which in turn stands for West Port, as in West Port High School. Or it could be the "wp" in wolfpack, West Port's mascot. This term originated among the more ghetto students at the school in Ocala, Florida.
Person1: Ayyo, let's go in dat store.
Person2: Why? They ain't got nuthin' but dub-P fashions!!! (white people clothes)
Person1: Yo...wat we gone do 2day?
Person2: Lets go chill wit tha dub-P's!!!!
Person1: You so crazy!!!!!