That person that's a part of your chorus that you just can't stand.
Roberto is such a chorus cunt, I can't get along with him!
In British pub and restaurant culture when a server drops a plate or a glass, a Cunt Chorus is when some of the restaurant customers jeer or mock them loudly with the intention of making the server feel bad. This is more prevalent in poorer areas.
"Why did the waitress go home early?"
"She dropped a plate, and the Cunt Chorus made her cry."