I'm going to blow off my niece after she said I smelled bad
How are you going to blow your niece off?
I told her she stinks of cheese and so does her dad.
While it is rude of your niece to comment on your hygiene, sinking to her level and insulting her and your brother makes it even worse. If a child comments negatively about you, tell their parents to correct them, don't insult a kid.
Dude, she's nine. She doesn't know what she's saying. Also my nephew has nits.
I'm just saying that insulting a child isn't going to help your situation. You should just let her say what she wants if she's that young.