Karen

A middle aged (usually caucasian) woman with a unhappy homelife who takes her frustrations out on store clerks and restaurant employees, because she doesn't have the nerve to stand up to her husband/boyfriend or has no control over her children. Her favorite thing to do is to hold up a long line while trying to return something she bought 2 years ago with no tag or receipt and expecting cash back.

That Karen's holding up the line! Who does she think she is?!