You'll almost never hear people refer or greet each other with the term 'nigga' here in the U.K and for the record I'd say that the same applies
to other European countries including the ones from down under (
@Adheer Warsame @Transparent @TheLibertarianQuiche). We use it on the internet an what not I guess but outside of it it just comes off weird since it's almost never used/or unintelligible when you have to connect it with every other word. That's not to say that we don't throw it around
in a comical sense from time to time though, it's not a term of endearment for us.
We don't habitually throw the word around like you mans across the pond that said you'll find a handful of people who do to be "hip".
Thaaaaaaaaaaaaaat said, I find the whole 'only black people' could say it thing preposterous.
Haa la isku waasho!