Reverse negrosis 

When a black person calls a white person a "nigga" but doesn't like it when the white person says it back. Also referred to as a "one way nigga."

Black person: Waddup nigguuuuuuuh?
White person: Yo. Waddup my nigguh?
Black person: What the fuck did you just call me?
White person: Yo man. That's reverse negrosis.

Reverse negrosis by ElJameso April 14, 2015

Reverse negrosis 

The medical condition in which a black person turns from a black person to a white person. Some symptoms may include the lightening of hair and skin tone, the shrinking of lips, losing the urge to eat fried chicken and watermelon, listening to more crappy pop music like Justin Bieber or Taylor Swift, the increase in the pitch of their voice, and their inability to rap as well. It is often contracted from being exposed white people for an extended period of time.

Black Guy 1: Dude, you got so pale over the summer!
Black Guy 2: Yeah, I'm suffering from reverse negrosis.

Reverse negrosis by newtonfig May 15, 2013