You suck. No, not you. You

A conversation in the car today:
Background: I went to go pick my sister up at school and I stood and waited for her at the corner. And then we go into the car.
Sister: I didn't see you.
Me: I was like the only one wearing red.
Sister: Yeah, but I thought you were someone's mom.
Me: (shocked) Someone's mom! (turn to my mother) Did you hear that? She said I look like someone's mom!
Mom: Did you say your sister looks like someone's mom?
Sister: (nonchalantly) She looked like someone's grandma.