I have weird cases in which through RP. Characters that I know/know me, I will go up to and make a vile remark, and if it's someone like Sam 'Stunner' Abrahms, you're damn well right I'm gonna mention his race. But in a more fun loving way. IF I were to put input into the situation. As long as someone isn't specifically screaming 'NIGGER' at black marines, or 'SPIC' at Spanish marines. It should be fine.
Again, I have several people I use these terms on. One case was a marine back in Banter that was a Texan Mexican, and everyone called him 'Boarder Jumper' and 'Texican' or outright 'Spic.' I guess you'd need to factor in the context of it too. A simple 'My Nigga' could be abused by MPs to arrest someone.