In musical theater, a 'charm song' is a number in the middle of the show that serves no plot purpose but to make people endear themselves to the characters and the show. On Broadway right now, go check out Ragtime for a great example, in the baseball number 'What a Game,' which doesn't advance any story but is cute, fun, and drives home a larger point in the show.
It's very intense. I know when we made the show, the first year, when it took off. We're supposed to make 12 episodes or something. We wound up making 50 episodes the first year. We worked every single day except Thanksgiving and Christmas. It is really tense. You are living in, like, a motor home together and getting ready on location. And everybody, you know, you get a little edgy.