Luna has just been defeated as Nightmare Moon, and is settling in nicely at the Canterlot Palace as a filly. Celestia, however, hasn't gotten used to all of the crazy things the young Luna can come up with when still in this adorable form. One day, she gets this wild idea that the moon is somehow made of cheese. At first, it seemed harmless enough to allow Luna to think this. Although, then she starts talking about how Celestia's sun is made of custard.

Celestia throws dignity out the window, and attempts to correct her much littler sister on this error. After all, how could the sun possibly be made of custard?