Carla: Diane, while I'm thinking about it, I need tonight off. Could you switch with me?
Diane: Uh, well...
Frasier: Why not? There's nothing going on in our lives.
Diane: That will be fine, Carla. You're in luck again. It seems every time you want to trade nights with me, my plans get cancelled.
Carla: Yeah, go figure.