Short answer

Oliver: Mommy, I like that tissue box.
Mimi: Well, when it's empty maybe you can make something out of it. I used to do that when I was a little girl.
Oliver: And me too.
Mimi: You were a little girl too?
Oliver: No, I was a little boy. But I'm not a little boy anymore. I'm a big, big, big, big boy.
Me: Really? Where did the time go?
Oliver: It's on the clock!