Unable to return to Ponyville after the Gala due to the spell on their carriage wearing off, and it being too late at night for anyone of them to pull it, Twilight and her friends end up having a slumber party with Luna, thanks to Celestia. This bit of information thrills Luna, who apparently enjoyed the destruction of the Gala. This is going to go very well, or very badly. Or just very strangely. Whichever happens first.

(This was written for the Happy Luna contest on Equestria Daily months ago. And I couldn't find an image that fit well enough.)