Everybody hates everybody else. When people look different, that becomes the easiest target for small minds to pick on. If the kid came off as white, they would have just called him a faggot instead because they have nothing else better to do with their pathetic lives. What the OP described was a bunch of 14 year old kids with the protection of anonymity on their side. If you were really this offended when a bunch of anonymous teenagers said "nigger" to someone that they don't even know is black, then you have no idea what real racism is...and that means society has come quite a long way in only a couple of generations.
NIGMAN: JRRRR IS A SHIT
NIGMAN: HO ESLE THINK IT??