A female (the male term would be baristo) who holds up the line at a fast food soda fountain because she fills her drink then leaves it in the way so she can get a lid, sugar, straw, etc. instead of moving the drink out of the way.
She doesn't care that she's in the way and holding up the line. In fact, she may feel so important that she is entitled to do this!
It's the same kind of conceit that one finds in people talking on cell phones while driving too slowly and not paying attention to others.

to sport a boner, fly the sail at full mass, rock hard, etc.