Tell me about it

Peanut: Oh my God.
Me: Don't say "Oh my god."
Peanut: I can say it if I want to.
Me: No you can't.
Peanut: Yes I can.
Me: I said you can't, and I'm the Mom of you.
Peanut: No you're not.
Me: Oh yes I am. I gave birth to you.
Peanut: Ew. Nasty.