How do you get over the social anxiety of looking like an idiot?

Look around. Most of us look like an idiot occasionally to somebody. Usually, mostly, to ourselves! 

Experience is the only teacher.  Spend time socially, get more comfortable.  EVERYBODY has "idiot" moments.  My idiot moment?  I was at an office Christmas party.  A woman came in dressed in a floor length low cut LEOPARD cut gown.  Quite the look for an office party.  So I turned to the people I was talking to and said, "Who is THAT in THAT dress?" and one of the people said, "Haven't you ever met my wife?"  I could have died.  I laughed it off, said I was jealous, but talk about looking like an "idiot."  I don't drink.  I can only imagine what I would have said if I had been drinking.