You know what, let's make it official: What would happen if you could spend the night at each of the main six's homes? And they're there, as well as whoever else normally lives there.
Twilight: If magic is as scientific as the show makes it out to be, we would probably spend half the night geeking out about the mechanics behind all the different spells. Though at some point, I would probably have something to say about putting books back on their shelves. I mean, I leave the occasional book lying around like normal people often do, but having half the library on the floor is just silly.
Rarity: Honestly, I might get bored. I don't imagine we have much in the way of shared interests.
Applejack: Best. Night. Ever. Granny Smith might have a story or two to tell around the dinner table. Big Macintosh, I think, might be interesting to observe, whether or not he actually says full sentences more often at home.
Pinkie Pie: I appreciate the gesture, but if you're calling it a slumber party, aren't you actually supposed to, you know,
sleep at some point?
Fluttershy: I think I might get her to open up just a little bit if I take the indirect route by interacting with the animals instead. Otherwise, it'd be awkward silence all night long, and nobody wants that.
Rainbow Dash: I fall through the cloud to my death.
Bad End