1.a member of the male species homosapien (dependent on era), characterized by an perennially dirty quality (not unlike pig-pen from chuck brown)
2. a male who always forgets to shower and has no good excuse for his dirty appearance or nauseating smell.
Rick used to come over uninvited to my friends house with a dirty face and clothes. He'd glare at you because you were clean. He was such a poobutt.