Someone who's wit(thoughts) are mainly based on getting fucked. They constantly think about how to get fucked and come up with sexual definitions for normal words on urban dictionary. Their language is also full of innuendos in normal conversation which should suggest they need eugenic neutering to reduce their over-active sex drive.
Ninety five percent of people on urban dictionary are fuckwits. Eugenics would create loads of blue eyed blonde racists.