Variant of "Racist", as spoken by black people.
What black people will call you, if you disagree with them or make them angry in any way. Its usage is typically preceded by a vaguely understandable smattering of ghetto slang and misspoken words.
Man 1: I disagree with President Obama, as I think his policies are somewhat Socialistic and he is slightly inexperienced.
Man 2: Yo dawg, you a mothafuckin' raciss, you just don' wanna be ruled by a BLACK MAN.
Customer 1: Good evening, reservation for two.
Waiter: Right this way, sir.
Customer 2: Resuurvation?! I don' got one, yo. Y'all muthafuckin' crackas just don't wan no niggas' up in hurrr. Y'all Raciss.