Big-Year-Old, and Beyond

David and I were in the car, talking about his play date tomorrow at Chase's house.

Me: Chase has a brother named Charlie too!
D: Yeah, I know. Except Chase's Charlie is a baby and my Charlie is a big kid.
Me: Yeah.
D: But when Chase's Charlie is a big-year-old, then he can be friends with my Charlie.
Me: Well, by that time your Charlie will be a teenager.
D: Yep, he sure will. ... Mommy, how old is a teenager?
Me: Any age that ends in -teen: 13, 14, 15, 16, 17. Like that.
D: Is 18 a teenager?
Me: Yep.
D: I want to be 18 when I'm a teenager.
Me: Yeah, 18 is a fun age. That's when you get to go to college.
D: I want to go to college. And then I'm gonna gradulate.
Me: I know you will graduate from college, because you're a smart guy.
D: And then after I gradulate, then I'm gonna go to State.
Me: To where?
D: State.
Me: What does that mean?
D: I don't know.