If the person says she has a Black boyfriend, couldn't you just say, "Nice, I hope you'll be very happy together, but (whatever she just said) is an argument used by racists against Black people like your boyfriend and his family, and keep in mind that you owe them loyalty, and you don't want to be accidentally spreading slanders or ideas that hurt or endanger them." It's a little like that "coon's age" thing. Good grief, I never thought of that being racist! I'm one of those who assumed they meant real raccoons for some reason. I don't think I've ever said it, because it's not a thing my family ever said, but that's only the same reason I've never said "land of Goshen" or "by crikey." Yikes! You bet your life I'll make sure I never say it now that I know about it. There are all these verbal land mines that have been planted, and we all need to begin pointing them out.

Maybe I'm not understanding.

Just because you have a black friend does not mean you are not racist.

I had friends where I worked. They made sly innuendos about people different from them. I usually elbowed them, they just went on.