Uncle Bruce is teasing B.
Bruce — B, if you want, I can trade you your DS game for the poster of Grandpa that you got at the White Elephant gift exchange last night!
B — No! You can’t have my game!
Bruce — You don’t want to trade?
B — No! You can’t have this, because it’s fragile!
Bruce — Well, that’s okay.
B — If you drop it one, two, three, four, five, six, seven, eight, nine times, it’ll break.
Bruce — Are you sure? Let’s count. Give it to me.
B, alarmed — No!
Bruce — I’ll prove it.
B, loudly and emphatically — NO! You don’t have to prove it with my most favorite thing!