Chris Brown's ex-girlfriend, Karrueche Tran dropped the N-word and Twitter did not like that!  She thought her mixed racial background gave her the okay to use such language, obviously Twitter thought otherwise.  She tweeted:

"If you a real n*gga, then f*ck with me.," she tweeted January 27th.
"I'm half black so I can say n*gga lol"
"I guess I can only say NIG" (Karrueche Tran's Twitter)

Karrueche merely quoted Atlanta rapper Trinidad James' "All Gold Everything" hit record but didn't edit the lyrics.  Of course Twitter went off on the Vietnamese model. 

There's so much sensitivity with this word and such a fine line but I think people definitely take it overboard.