[ ...Now, they're getting into the real nitty-gritty of it, and something eases off Prompto's chest at the question. He can't help a chuckle — sorry, buddy — because the prince isn't gonna like his answer... ]

Seein' as we passed my b-day while we were there? Yeah, I'd go ahead an say I am. You're lookin' at a ripe, old twenty-one year-old Prompto now. I know, I know, the wisdom just radiates off me.

[ Or something like that. Given the opportunity to run with this joke, he will, because puts distance between them and the bomb he's just dropped on Noct. There's going to be more to cover, but they can get to those things eventually. For now, just let Prompto harass his buddy in peace. ]