Maybe it’s day five of the tour and he’s just still tired, or maybe Kate said something to set him off, but Prince William suffered from a major case of the giggles in the Yukon today. 

The Prince—who’s generally all bout that stiff upper lip life—was clearly having a ball watching a children’s performance during a traditional First Nations welcome ceremony. Kate’s also looking rather cheery, but Will…well, at least he was enjoying himself. 

The couple had actually sent out their first joint tweet earlier that day, so maybe it was just his sheer relief at passing a milestone most of us reached in 2009 that was making him giddy?