Ways to teach my sister a lesson?

My sister is a funny little girl most of the time. But there are times when she says things that aren’t nice. She constantly makes racial slurs towards African Americans. She says she doesn’t like them, whenever she sees one she says things like “I better hide, I don’t want to get shot!” in a non-joking way. I’ve recently heard her tell my other sister that she doesn’t like a girl in her class because she’s black. My sister is 10 years old, you’d think she would know better. Well she doesn’t. No one in our house teaches her these things.

My parents have never bothered telling her that those comments she makes are rude. So she continues making them, when I tell her to stop she completely ignores me. I have decided to take things into my own hands. Any ideas in what to do to scare her so she would stop?