This is why I disagree with the use of ethnic slurs in ANY context, even as a joke, even to people you are very close with and even towards yourself or your own ethnic group. While context does matter and people should be able to tell the difference in a racist or a non-racist use of a slur, it's easy for people to try to excuse their use of slurs when people of colour are using them, it can diminish your own moral authority to call it out if you use them, and it just muddies the issue unnecessarily for people who are not that evolved and gives them easy excuses, in my opinion.
If I see people writing words like cracker and mutt on facebook, I report that. I don't want to see that and it offends me.
Get used to me. Black, confident, cocky; my name, not yours; my religion, not yours; my goals, my own; get used to me. -Muhammad Ali