It's the dawning of a new era: Ezra has started wearing underwear! Up until now, he has always gone commando. But now, he feels like wearing underwear.
He was excited about this and showed his neighbor-friend his new pair of boxers, while he was wearing them, and the neighbor-boy was, like, "Uh, yeah." Clearly not understanding Ezra's excitement and probably figuring that everybody already wears underwear to begin with, so why should that be a big deal? Well, it is a big deal, neighbor-boy. It is.