Over the years, Applejack had learned that Twilight Sparkle was the kind of mare who generated questions that were best left unanswered, second only to Pinkie Pie. Pinkie hinted at Things that a sane mind and experienced baker recoiled at. Twilight just lectured at anypony who showed a hint of interest until they begged for mercy.
Still, there were some things that Applejack just couldn't let lie. "Um, Twi? Why's Princess Celestia sleeping at the bottom of yer bed?"
Twilight glanced at the princess of the sun asleep on her floor like she was looking at an old throw rug, shrugged her wing, and turned back to her paperwork. "Oh, minor spell accident. She thinks she's a dog."
"Oh....kay." Good news, Twilight considered the matter settled. Bad news, that just raised more questions. What's that mean, exactly?"
"Oh, if she sees something wrong, she barks at me until I fix it."
Applejack mulled that over for a moment, then grinned. "So... nuttin' really different then, eh?"
Eventually, they did call for Luna, who seemed distinctly unamused with Celestia panting with a dopey grin on her muzzle. "Sister, this is most unbecoming of you. If you wished to spend more time with your student, you merely had to ask."
"Wuff."
Luna rolled her eyes and held up a length of cloth in her magic. "Yes, I did get your leash. But—"
"Wuff."
"Well, admittedly you get to sleep with her, but... hm..." Luna trailed off and pondered the matter for a moment. "Does Big Mac have a dog, perhaps?"