Living with Sissy

I was in the shower this morning and my sister came in to brush her teeth.

Beth: Are you going to eat the leftover beans for lunch today?
Me: Are you?
Beth: No I don't want to bring a lunch today.
Me: Then I'm not going to either.
Beth: Why not? They'll go bad.
Me: If you're not going to eat them then why should I have to?
Beth: I don't want to bring a lunch today!
Me: Well I don't want to eat leftovers!
Beth: You're so annoying.
Me: No, YOU're so annoying.
Beth: No, YOU're so annoying.

...aaand we are both so mature.