When Twilight and her five closest friends from Ponyville walked into the ballroom, a dazzling array of sights and sounds met them. Court nobles stood around in fancy dress. Upon an elevated stage, several musicians played elegant, unobtrusive background music. (Rarity took note of the cellist's perfect, pink bowtie.)
And at the far end of the room, a broad stairway and elevated throne displayed...a tall, pale-skinned, completely naked woman. Her keen, attentive eyes spotted the six newly arrived guests, and her hand beckoned them to her.
The six young women obeyed her welcoming yet commanding gesture almost reflexively, crossing the room and walking up the throne dais' stairs.
"Welcome to the Grand Gala!" Princess Celestia's smile beamed radiantly, her arms open wide.
"Hugs!" Twilight squealed, leaping up at her old friend. "You give the very best hugs, Princess!" Twilight squeezed the amazonian sovereign with all her strength...which, to be fair, after Twilight had hauled and hoisted the largest, thickest, heaviest books every day of her life both singly and in boxes and bales, was not inconsiderable.
Celestia made a tiny squeak, and hugged Twilight gently but firmly. "I missed you, Twilight. Most of my court doesn't put in the work to build as much physical hug strength as my very favorite, most faithful student." Celestia kissed Twilight on the top of her head, carefully not mussing the purple librarian's hair. "I could just eat you up! Speaking figuratively, of course."
Celestia added, "And these must be your friends." As she spoke their names, she nodded to each one. "Applejack, who probably gives hugs even more muscular than yours. Rainbow Dash, the very cool athlete. Pinkie Pie, who looks like her hugs are so soft and warm. Fluttershy...Twilight's letters never said how beautiful you are, my dear. And Rarity...the clothing designer? You are indeed as gorgeously stylish as Twilight's letters described."
Rarity blushed. "Thank you, your highness."
Twilight pulled her face out from the depths of Celestia's alabaster cleavage. "Does everyone else want a hug too? Celestia's really are the best."
Applejack blushed. "I...um...pleased to meet you, your majesty. But I think I've got to do something with some apples, before I get so close up and intimate-like with a real life princess." She muttered, "All bare nekkid."
Rainbow said, "I see some Wonderbolts over there! Got an urgent message for them."
Fluttershy said quietly, "I think a racoon in the garden is in trouble! I have to go help him!" She ran out of the room, dodging between the crowds.
Pinkie said, "Wheeee!" She ran up beside Twilight and Celestia, hugging both of them for a moment. "Wow. I sure am short. Either that, or Princess Celestia is really, really tall."
"I am indeed the tallest in all the land," Celestia agreed. "When it comes to events like these, that is my great sorrow, and an inconvenience to so many. My height prevents me from participating in at least one important part of the Great Gala."
Twilight changed the subject. "So, who wants some punch?" She looked up into her mentor's eyes. "Would you like us to get you some punch, Celestia?"
Celestia smiled. "No, thank you. The servants bring it to me in...extra large cups, as befits my stature. To someone like me, the regular cups are almost like thimbles."
"Oh!" Twilight said. "I should have thought." She chuckled. "You girls should see how big her teacups are."
With her face mashed against one side of Celestia's chest, Pinkie said, "Her teacups are really big! I mean, humongous. I didn't know cup size letters even went up that high, but now I'm a believer!"
"So," Rarity said, blushing as she simultaneously marveled at Celestia's nude spectacle and tried not to look at it, "You really are as amazing as I've always heard."
Celestia smiled. "Thank you, Rarity. You are too kind."
"Not at all!" Rarity said. "Now...I think I should drink a bit of punch myself. Or go sit down. I seem to be feeling a little faint."
Twilight said, "Let me help you. I don't want anyone falling down the stairs again. It always makes such a commotion." She released her grip on her mentor, and put an arm around Rarity. Step by step, Twilight helped Rarity down to the room's main level.
Twilight insisted on half-carrying Rarity all the way to a row of empty chairs in a quiet corner. "Here you go," the librarian said. "I know meeting Celestia for the first time can be overwhelming."
Rarity sank into a chair. "I never would have expected it. I mean, I've heard stories, but I never thought it would happen to an Equestrian monarch."
"Whatever do you mean?" Twilight asked.
"The story of the Emperor's new clothes."
"I don't see how that applies," Twilight replied.
"But surely you've encountered the tale? A pair of slick salesmen come to court, bragging about their wares. The salesmen say, their clothes can only be appreciated by the most discerning and refined taste. Only those of true noble blood can see the garments...to peasants, or to people whose blood is tainted by commoner ancestry, the garments seem invisible."
"I never understood that part of the story." Twilight snorted. "Doesn't everyone have commoner ancestry, if you go back far enough?"
"I suppose..."
"And if the Emperor thinks it's so important to dress up so fancy, why does he want to let all the commoners see him naked?" Twilight shook her head. "No, Equestria's sovereign is far wiser, and completely even handed and fair. She lets everyone, noble and commoner alike, see her the same way. Without discrimination or pretense."
Rarity blinked. She thought for a moment. "I suppose?"
"Princess Celestia has absolutely nothing to hide!" Twilight said proudly.
"So...I suppose you mean Princess Celestia at least isn't the victim of a gang of confidence tricksters selling clothes that don't really exist. That, at least, is a relief." The perplexed designer continued, "But I still don't understand why a princess who could choose from the very best work of any designer in the land has decided to walk around completely naked. Especially at the fanciest, most elegant event of the season."
"That's exactly the reason!" Twilight said.
"Excuse me? I do not follow."
"In order to dress up for the Gala, Princess Celestia would have to choose. One designer would get the contract, and all the other designers would feel left out. It wouldn't be fair. If the palace is buying oats, any servant can go out to do the shopping incognito...and goes out to different shops in turns, so no one shop can brag of being 'the royal favorite.'"
Rarity's great self-control in the service of beauty succeeded. She did not furrow her brow, or chew her lower lip in frustration.
"But a princess so much taller and more statuesque than anyone else can't buy off the rack," Twilight explained. "In standard sizes, even the very longest dress would only come down to her thighs. Maybe her knees? It would look ridiculous. And she has a very large ribcage, you know, so the dress would probably rip in two right over her chest."
Rarity imagined such a fashion faux pas in the middle of the year's most prestigous formal event. Her pale complexion displayed a heated pink blush. "How dreadful."
"Yes, so it's really better this way. Because otherwise, every year at Grand Galloping Gala time at least one designer would be completely insufferable, and everyone else would rush in a huge stampede to get clothes from 'Princess Celestia's favorite designer.' It would be terrible! And completely unfair."
Rarity said softly, "So...I couldn't help but notice that your mentor is...a bit large in the chest. In front, I mean."
"That's true!" Twilight agreed. "When I was a tiny foal, sometimes I used to nestle in between them to take naps. I felt so warm and safe in there!"
"I...um...I suppose I can picture it. What a completely adorable sight, I'm sure. But with such a...large pair...doesn't she feel the need of support?"
Twilight grinned. "An alicorn is immortal, and completely immune from the problems of aging. No wrinkles, no butt sag...and no need for support higher up, either!"
Rarity finally bit her lip. "The mind boggles."
"Celestia really is amazing," Twilight agreed. "And if we're lucky, we might get to see her sister in formal dress too."
"Um...I'm sure Princess Luna presents an equally remarkable spectacle...being entirely as beautiful, but in at least one regard exactly opposite in appearance."
"She does!" Twilight agreed. "At a very formal, fancy event, Princess Luna is indeed the opposite of her sister. Princess Luna runs in and out of the room every five or so minutes, each time wearing a different off the rack outfit from a different merchant. Hay-Mart, Tarzhay, Wallflower-Mart...she doesn't leave anyone out. That's how important it is to the Royal Sisters not to play favorites!"
"Yes..." Rarity said faintly. "How...even handed of them."
"The princesses really are the best!" Twilight agreed.