From the last name of an afro-american slave that escaped from his owner, got caught and have been hanged with all his familly, in 1743.
Now it defines very unfortunate people, or persons from poor countries such in Africa or Haiti. It is also frecuently used in computer games such The Sims, when your black character(s) die(s)
guy 1: Yesterday, my friend missed the bus and have been hitten by a car as he was running after it...
guy 2: Ow, he,s such a N'Bonagoy!
Guy 1: I saw at Tv those men from Angola, that was so sad!
Guy 2: Yeah i know, they're N'Bonagoy...