That might be your black friends that are cool or say that they are cool with it. Perhaps there's no sting to the word with them, maybe they've never had that word said to them with hate and disdain behind it. They might live a life that is safe and where they don't feel as though that means anything.

I have a lot of white and non poc friends. None of them are ever welcome to speak to me in that way, nor am I fine with them saying it infront of me. I'm nearing 30 now so I can't be jumping on anyone for just saying it but they would for damn sure be permaneny dismissed. But that's me and my black friends and family, seperate from yours and living much different lives.

Try to keep your 'It's cool, I'm down. I'm one of them' contained to yourself and your friend group. As a non-black there is a level of power and class (perceived or otherwise) you posess whether you recognize it or not and the fact that you have the choice to do and use whatever language that you want without concern for or the ability to comprehend how a marginalized group that has wildly varying experiences might think or feel about that is kind of proof of that.

It's really late so hopefully this makes sense. Seriously though, not cool. Please don't teach people that it's okay and that there is a difference, that is a you and your friends thing, not how the black (American) community feels.