There's something inherently subjective about fun. What is fun for me might not be fun for you. If you force your idea of fun onto me, even if it's fun for you, it's not going to be fun. I think that there's something to the fact that fun may more often than not be a social experience because we know that the best data is always anecdotal.
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?