A combination of "whats up dog?" and "whats up though" making it both a freindly greeting and a question at the same time. Origins in Rochester and Detroit Michigan.
Garden variety male douche bag. Frequently seen wearing multiple bracelets,several earings,a backward hat,shorts that are way too big,and driving a jacked up jeep wrangler, that most likely belongs to his mom. A Sup Dog will frequently fake some sort of ghetto persona, he is however from an upper middle class,surban family. A fake ghetto frat boy.
Person 1:Sup dog. Whats up? Person 2: Hey. Nothin much just chillin. Person 1: Sweet, can I join? Person 2: Sure bro, just grab a chair, sit back, and relax.