"I feel like a little more confused about fun than when we started with Sid's question," he says. "It is a mystery, but I think that it does draw on a lot of these things where you know that it's playful." He adds: "The fact that tickling is something that is kind of painful, sort of, right?"
Why does time fly when you’re having fun? How do you teach rats to play hide and seek? And what does all this have to do with Anne Boleyn?