@chakra12 Did you ask where she heard it?
My son had a similar issue and it turns out apparently it's thrown around out his school like nothing between the kids. Non of them were saying it with intent to insult, they were using it as a greeting type thing.
Idk what kid started it, or how but I had to sit my son down and give him a talk about it, the history of it and why he in as a white person should not use the word.
I had to specifically tell him that because he was rather confused and asked why I have never said anything to his friends when I heard them, I told him because they are black they can choose to use or to not use the word. It's simply not my place to decide that.
He hasn't said it since from what I'm aware.