Funny Comeback

So I go to McDonalds to get a drink when I see this fat girl bullying a mentally disabled kid. So I walk up to her.
Me: You know that can happen to any of us, right?
Girl: Well God gave me a mouth to speak with so I'm going to use it
Me: Yeah? Well God gave you a mouth to eat too, but you abused that privilege, didnt ya?
Girl: -Speechless-
Me: Wipe that ketchup off your chin, too.
Girl: -Wipes chin-
Me: No, your other chin.