when used in the context "give her/him the sick nicers"...sick nicers refers to when you are rootin' someone and in the middle of it you call up your buddies and yell "SICK NICERS" into the phone.
A person who displays racism and/or belief in stereotypes without actuallyhating on different races or faiths.
Person A: "Black people are the best musicians! They always keep the rhythm."
Person B: "Dude, that's niceist."
Person A: "I should go and ask Li to tutor me in math. I mean, he's Asian."
Person B: "Seriously, stop being such a niceist. Li just got a D in his math test."
Person A: "God, all Italians make amazing food."
Person B: "Man, there's good cooks everywhere in the world. Now shut the fuck up, stop being a goddamn niceist and eat your friggin' pizza."