"This is a dumb idea."
"Exactly, that's why we are doing this!"
The royal guard in Canterlot is among the best of the best. Boasting the best in discipline, loyalty, skill, and more, only the best of the best were allowed to join its ranks. For Lieutenant Sharp Eye of the night watch, patience, temperament and lack of sarcasm were not at royal guard levels. To the pegasus stallion's credit, though, it is difficult to be cheerful when one is one of two creatures pushing a trebuchet from the armory into the gardens.
"Her majesty is going to kill you if you mess with her flower arrangements this close to the zebrican ambassadors visiting," he warned.
His companion, the only human in the world, chuckled and ruffled Sharp's mane. "Don't be an idiot, Sharp. I wouldn't DARE mess with Celly's precious... whatever flowers these are. Worst I'll get out of this is the usual when they catch me. Now man up and help me push this thing!"
"I'm not a man."
"Pony up, then!"
It took another hour to get the siege weapon into position. Had any other creature been seen pushing a trebuchet up to the inner walls of the castle, they might have been arrested for high treason or worse. But Nick had a certain 'diplomatic immunity' when it came to the over-the-top pranks he and the diarchs often pulled on each other, so most staff either turned a blind eye or decided that other areas of the castle needed their attention more than the current location. Pushing up a cart full of bags and a chalkboard, Nick started making basic calculations in between loading the mystery bags into the trebuchet while Sharp stood lookout.
"Any pretty pony princesses come by?"
"Nick, I do night watch from the top of the north tower three days a week. If I can spot a robbery in the market from there in the dead of night, I THINK I could spot our benevolent rulers."
Nick snorted in jest, a habit picked up from his equine friends. "I prefer calling them 'above average horses', mainly because of how defensive you guys get."
Sharp frowned, but shook off the thoughts of that argument for a more pressing question. "So Nick, what exactly are you planning?"
Finishing setting a magic crystal to fire the trebuchet later, he smiled his trademark 'prank time' smile. "Oh, just imitating one of the greats."
4 hours later:
The sun peeked over the top of Canterlot mountain as it began its slow descent, and dozens of very high-class ponies gathered in the central courtyard of the castle for a very important event. Nick was among them, wearing a fine suit custom-made for him by a certain generous fashionista, and enjoying a glass of wine with his best friends, Celestia and Luna. All three seemed happy together, but a trained eye could tell all three had something planned, not that they let any clues slip.
After an hour of enjoying time together as friends, the diarchs stepped up to the podium located on one side of the courtyard to give a short speech. "My little ponies," Celestia began, "We are gathered here today to celebrate each and every one of you, the best artists, painters, and sculptors Canterlot has to offer. Of course, art is nothing without a subject and an audience, so some of Canterlot's elite have come to see all your hard work over the past year."
Luna stepped forward to continue. "Furthermore, we hath summoned a great artist to have the honor of painting our sister and ourself, so please welcome the otherworldly artist, Nicholas Abernathy!" Hooves stomped the ground in applause as a unicorn shone a magical spotlight on Nick, and a pair of guards escorted him to the stage. The sisters had comically wide grins as Nick was all but dragged to the stage, but those grins faltered as he left the guards behind and walked up to the easel and canvas without any prompting.
"So, you called me here to paint the two of you in a way only a human can, hm?" Nick asked, choosing to sport a comically fake French accent.
Celestia and luna began to sweat nervously at their prank victim's sudden confidence. As a psychology major, Nick could barely draw a straight line, let alone a Van Gogh level masterpiece! "Y-yes, we decided to have you come and paint us, as you are the best human artist we know and we thought showing the elite members of the local artistry guilds human culture would be a great opportunity for them to grow. It's not as if you are really a terrible painter and would be a laughingstock, right?" Celestia inquired, hoping to tease the human with his imminent humiliation.
Luna cut in, her voice echoing through the courtyard. "Enough stalling! Paint us!"
The sisters froze as Nick grinned. They knew in that moment that they were about to suffer. Nick simply raised his hand, holding a small crystal, and threw it to the ground, activating it.
"With pleasure."
On the other side of the courtyard walls, a trebuchet launched gallons of glow-in-the-dark pink paint at the center of the platform, drenching both the solar and lunar diarch. As everypony stood stock still while their brains rebooted from the shock, Nick bowed to the crowd. "Thank you, thank you! You are all too kind! The princesses have been painted. I live here, so I'll be here all week. Toodles!" With that, Nick dashed off, vaulting over the guards and sprinting through the first archway he reached. As he ran, cackling like a madman at his latest prank, he covered his ears and braced for the inevitable.
"NNNNNNIIIIIIIIIICCCCCCCCKKKKKKKK!!!!!!!"
That night, after a long chase through the castle the tracked paint everywhere, Nick was given his usual comeuppance, as he predicted. "Any last words?" Celestia asked, her and Luna's coats still softly glowing as they held Nick in the air with magic.
"Yeah, you two look really nice. Did you do something with your fur?"
And with that, Equestria's only human was dropped from the balcony into the moat below, for the third time that month.