If the worst slur for blacks was somehow turned right around on whites it would be something like whitey, maybe white boy. So these things don't really make sense.

Cracker still means basically nothing. I don't know what the worst thing you can call an Indian is, but the worst thing you can call a black is black, apparently, and the worst thing you can call an Indian is Pakistani. When you are slurring someone, I don't think the words make sense.