However close we get to an equal society, there will always be people that assume superiority and hate the fact that they aren't and other people that hate them for it. The "superior" use insults as a weapon to suppress, so "the joke" is an excuse and never funny. The others use jokes as a weapon to enlighten the undecided and belittle the superior and that's the reason they're funny. And some people are neither, they just laugh when something's funny.
Not in the context of the interaction, two friends, the colour of which is immaterial, greet each other in the context of their mutual culture in which there's a myriad of reasons why "my nigga" is acceptable to both, no insult, not even a joke intended; the only possible reason for offense is, if the interaction is observed and even then it's only due to not understanding the context of the interaction.