fly in the buttermilk 

A single dark skinned person surrounded by a group of light skinned people. Possibly, but not necessarily a token black. A racial variation of fly in the ointment.

Jackson: This is my school picture from the early days of desegregation.
Williams: You look like a fly in the buttermilk.

Aaron did not realize that he had only been hired to make the company seem as if it promoted racial diversity. He became discouraged on the first day of work at the firm when he realized that he was the fly in the buttermilk.

fly in the buttermilk by gr8rt1 November 13, 2014

fly-in-the-buttermilk 

a black guy with low self-esteem who dates or marries a white woman in a poor attempt to raise his own social-class status.

I hate how a project nigga comes into some cake, and then next thing ya know, it's all bling, Benz and a wind-sprint to be another fly-in-the-buttermilk.

fly-in-the-buttermilk by vudu priestess June 6, 2010