When a blonde or a group of blondes develop a crush on a black guy in the southern regions of the United States, a Nazi Brunette infiltrates the blonde clique in hopes of thwarting a possible interracial romance when not based on monetary exchange such as a drug deal. Blondes have been taught to grudgingly yield to brunette advice, as they are percieved as the 'smarter ones', but the Brunette Nazi usually has a mean spirited agenda of manipulation and/or hatred for all parties involved. See also: buzzkill.
Barbie was doing just fine until that Nazi Brunette Tammy 'stumbled' into her life. Now Barbie's love life is completely screwed. Barbie had to move away.