It's A Binary Thing

Scene: Chinese New Year. Me brings home take-out, hands Teen a pint of white rice (she loves white rice) and proceeds to divvy up remaining takeout for the family.

Less than 3 minutes later:

Teen: Uhhhhh. I ate too much rice.
Me: I just gave you the rice! How much did you eat?
Teen: The whole thing.
Me: You're kidding.
[Teen shows me empty rice container.]
Me: Haven't we already had the 'eating slowly' conversation?
Teen: Yeah, but I eat fast for *you*.
Me: [blinks] What?
Teen: Well, just in case we're ever trapped in a life-or-death pie eating situation.