There are exactly five cases where a white person can use the n slur.
1) when they are in a play, movie or other production, and the character needs to say it (for instance if someone plays the part of a white supremacist in a film)
2) when they are quoting it, even though it's a better idea to just call it the n word
3) if they are telling someone the word, and anyway it's a better idea to just spell it out instead
4) if they are speaking Korean ('niga' is a Korean word I think)
5) if they don't know what it means or have been misinformed
THAT'S IT. THAT'S ALL. NO OTHER CASES. IT IS NEVER ACCEPTABLE TO USE THE WORD IN MEANINGFUL SPEECH, ONLY TO DESCRIBE OR QUOTE IT.