There are very few acceptable situations - for example, the "wassup nigga" greetings that are quite common between certain teenage groups now.Originally Posted by pasag
Of course, it's only acceptable when there are no black people involved (I've seen white/indian/chinese guys call each other niggas) or when there are only black people involved. Clearly shouldn't be used publicly, but there's no reason to get so anal about it otherwise. If the understanding is already there, using the term isn't such a big deal.
That said, I wouldn't use the term because I wouldn't want it to slip out at the wrong time (even if there was no bad intention, I'd get my ass owned as Pasag just noted).