Literally "fuck your race" in French. Translates as "fuck off" or "fuck you". Suburbian slang used to offensively send away or address refusal. It is sometimes considered as a racist expression because of the word "race", but its presence in slang expressions has become merely climactic (like "mère", mother).
Tu veux que j'aillle le balancer aux flics? Nique ta race bâtard! = You want me to rat him out to the cops? Fuck you bastard!
Qu'est-ce que tu fous là? Va niquer ta race! = What the fuck are you doing here. Fuck off!