This person, although they may be intelligent, lacks any resemblance of social skills. This person cannot function properly in a social environment and often embarrasses those around them with their attempts at doing so.
This refers mostly to making awkward comments, lacking common sense, or making inappropriate jokes in public.
That pathetic guy in every teen movie that desperately tries to get the girl, but makes the movie goer feel awkward watching him try.
Why is it that guys I think are amazing want nothing to do with me, but every loser, freak, and social moron drools all over me?