"Alright," Cadance said. "Random embarrassing moments, go!"
Celestia narrowed her eyes. "When will your villainy cease, Cadance?"
"Hrm," Twilight frowned, too. "I've got a few, but I'd prefer not to start."
"I vote Celestia starts," Luna piped up.
"Seconded," Cadance agreed.
"Third... uh, thirded," Twilight blushed. "Sorry, Celestia."
"Fine," Celestia grumbled. "Give me a moment. I need to climb out from beneath the bus you three threw me under."
After a pause of several moments, Celestia blushed and looked to Twilight. The two shared a long and knowing look.
"Drunk at the gala?" Twilight guessed.
"Drunk at the gala." Celestia confirmed. "Definitely not my proudest moment."
"Wait, this is new," Cadance said. "Why didn't you tell this story before?"
"Because it's definitely not my proudest moment," Celestia deadpanned. "I thought perhaps the evening would pass more swiftly with a glass of wine in my hoof. Then one glass turned to three. Bottles. Then it turned to scotch. Then brandy. And then all of them at once. It had been several decades since I'd indulged in brandy and I forgot how much I enjoyed the taste."
"Celestia: drunk," Cadance breathed. "I need to know what that's like."
"Twilight?" Celestia brought a hoof to her snout. "Explain for you sister-in-law. Most of my memory of that evening is a blurry headache."
"Uh..." Twilight scratched an ear, drudging memories she surely must have made vain attempts to repress. "Really... uh, really confrontational, to be honest. Like, she was convinced a bunch of little school-fillies were trying to out-drink her. She was all like 'I'm the bloody sun... sun... sun pony. Don't even tryyyyyy.'"
With the exception of Celestia, the princesses all burst into laughter at Twilight's mediocre impression of Celestia speaking in a drunken drawl. Celestia herself blew her mane out of her eyes and hid a blush with a hoof.
"Wow," Cadance said when she eventually collected herself, her eyes watering. "I need to see that for myself."
"I'm glad to see that a thousand years hasn't changed you that much, Celly!" Luna chortled. "Alcohol is still the bane of the mighty Celestia's regality."
"Every time," Celestia facehoofed. "Every damn time, I swear I'm not even going to touch a drop, because I know it will snowball. And like a fool, I figure that I've grown old and mature enough that I can simply enjoy one glass of pansy white wine."
"She'll drink a decades worth of restraint in several hours," Luna mused.
"Can we please move on to ridiculing somepony else?" Celestia moaned. "Luna, perhaps?"
"With pleasure!" Luna nodded vigorously. "My most recent embarrassing moment is most likely..."
She frowned.
Then, she looked to Twilight for help.
"Uh... your temper tantrum when no one recognized your Nightmare's Night costume, maybe?"
"Ah yes, that comes to mind. Especially because I took Celestia's by mistake and didn't notice, and then when I noticed, I had no idea who I was supposed to be."
"You were a devil," Celestia said. "And it was a brilliant costume."
Twilight snorted. "Less-so when your 'still-trying-not-to-look-evil' sister wears it."
Luna nodded. "Regardless I do think my increasingly belligerent assertions that I was supposed to be a pumpkin were quite hilarious in hindsight," Luna said. Then, she shook her head and grinned. "Alright, Twilight! You're up!"
"Ugh, fine," Twilight rolled her eyes. "Probably... uh, probably..."
"The time you accidentally sent me a belligerent letter intended for an editor at Canterlot Times?" Celestia offered. "Judging by the thirty subsequent apologies I received, I assume you were quite embarrassed."
Twilight blushed intensely, sinking her head in her hooves. "I started the letter off with 'Dear Insolent Moron...'"
"I remember the rest clearly," Celestia grinned. "'Dear Insolent Moron. Please take your effortless and slanderous gossip paper and shove it down your feces-spewing throat, you myopic excuse for a journalist. I'm sure your loved ones are greatly proud of you, that you've managed to make a living off of spouting lies about pony's personal lives.'"
"Geez, Twilight," Cadance gawked. "The hell's the backstory there?"
"It is... one for another time," Twilight blushed further, her voice distorted as she spoke into the table, her head still locked in her hooves in shame. "Isn't it your turn, Cadance?"
"Yes it is," Celestia said. "Go on, dear niece. Finish what you started, you monster."
"Very well," Cadance said. "Probably the time a guard dug up my first anonymous love poem to Shining Armor when I was moving to the Crystal Empire. Never did find out what happened to that. I'd written it in high-school and it was really freaking bad, and the damn guard read it to all of his comrades thinking it was for one of them."
Suddenly, abruptly, Celestia gave an uncharacteristic snorting laugh.
"That poem was written by you?!"
Cadance blinked, wordlessly prompting elaboration.
"I found it! In a dumpster outside the castle!"
"Wait, why were you..." Cadance began, but then a greater horror dawned on her. "Tell me you didn't..."
"I read it! I... I think I still have it, actually!"
"Don't you dare look for it!" Cadance shrieked.
With a flare of her magic, an old bit of pink paper appeared in Celestia's aura.
"Don't you dare READ it!" Cadance shrieked even louder.
With a flat, unreadable frown, Celestia unfurled the paper and began reading in a stoic voice.
"To my eternal love,
Well I mean kind of,
Cause like, I'm immortal and such,
And you're not and that's a bit of a crutch,
Anyways I digress,
But your heart I wish I did possess,
I mean I could take it if I was wanting,
But I think that's a family story that's a little daunting,
So instead I'll woo you with these words of my heart,
That I wrote from the depths of my heart."
Celestia finished, setting the poem down with the same stoic frown.
Silence.
Cadance gave a low, guttural growl.
Then, Celestia, Luna, and Twilight all burst into laughter.
"I was, like, sixteen, alright?" Cadance moaned.
"I think it's kinda alright!" Twilight offered, although her attempts to stave back snorting laughter seemed to run contrary to her attempt at helpful encouragement. "I mean, you rhymed 'heart' with 'heart', and 'crutch' makes, like, absolutely no sense whatsoever in the context it was in, but I think it has potential!"
"Who's stupid idea was it to share embarrassing stories?" Cadance growled. Then, she grabbed the alcohol menu. "Screw this. I'm showing Celestia how a real mare drinks."