Abbreviation for Nigger Blood. Way of saying Nigger Blood without drawing ire, or ramifications of Political Correctness. Reference to Black people who are free loaders, non hard working, blames others for their problems, abusive to women, driven by anger and stereotypical of negative attributes of Black people.
Guy 1: Look at that guy living off food stamps, free housing, and never getting a job.
Guy 2: I know. He's an insult to all us Black people, no wonder the others call him an NB!