Twilight was meandering along through the castle gardens when she heard a sudden splash. Then another, then another! It confused her, as few things impacted the water with such noise three times, so she decided to investigate. What she ended up finding were two of her best friends and a human all swimming in the castle moat. This concerned Twilight for three reasons.
One, it meant Nick had pulled a prank. Two, it meant Pinkie and Rainbow were in on it. And three, judging by the lack of Celestia and Luna, it meant this was one of the times Nick would voluntarily toss himself in the moat before the prank went off as to avoid getting either found by the sisters or thrown in again.
So of course she galloped off to go find out what was going on before anypony got embarrassed or hurt. Given that the yaks were visiting on diplomatic buisness, any little prank could set relations back and that would NOT be good.
Quickly, she managed to locate Celestia. "Celestia!" She quietly alerted her mentor. "Nick, Rainbow and Pinkie have pulled a prank! I don't know what it is, but given our visitors I would be on your guard! I'm going to go find what they did, you keep the yaks occupied!" And before Celestia could respond, Twilight was off like a rocket. She sighed.
"You know, just once I'd like a normal day where nothing goes wrong. Just one. Maybe if I went and at least told Nick about the yaks'... temperament, he could defuse the prank. I only hope Twilight has the common sense to confront him about it..."
"Nicholas did WHAT?" Luna's cry of anger nearly shook Luna's room.
"I think they set up a prank, and Celestia's busy with the yaks so we need to find it as soon as possible!" Twilight repeated. "Luna, do you know where we can check?"
"It would be in our best interests to forgo checking mine and my sister's rooms. We must work to scour the places the yaks will be before they reach those locales... Come, Twilight Sparkle! We shall make haste for the dining hall at once."
The pair raced to the grand dining hall, where tables upon tables of carefully prepared food to suit the visitor's tastes were being prepared. It honestly made Twilight's mouth water slightly, but she quickly steeled herself. She and Luna had a trap to find. Carefully lifting the tablecloths in her magic, she and Luna proceeded to investigate every chair, table, and conceivable hiding place for a surprise prank the grand hall could hide. Finding none, they proceeded to the throne room next. And then the library. And when the yaks left the conference hall for the day, they checked there too.
"Ah, this is the life! Chilling with my friends, good snacks, nice weather... could it get any better?" Nick asked aloud, having taken a break from swimming to lounge on the shore with his equine pals.
"No way I can think of," Rainbow Dash chimed in, stretching her wings and yawning. "You were right, swimming in the moat is a great way to pass time! How long has it been magically heated?"
"Since Celly threw me in one day during a snowstorm and I caught a cold. This is the only section enchanted to have temperature controls."
"Hihihi, it's like a hot tub! Do you think we could get one for Twilight's castle back in ponyville?" Pinkie chimed in.
"Maybe! But I thought we could all relax, what with those yaks always going off around me about the 'odd creature' they didn't ask for. Thanks for agreeing to spend the day with me, girls." Nick smiled. Truly, these fleeting moments were well worth the effort of having friends a two hour train ride away. "Hey, do girls hear something? Kinda sounds like Twilight screaming in panic from the castle..."
"Yeah," Rainbow added. "I bet she found whatever you set up. Hey, what kinda prank did you pull on the princesses today? I bet it was a good one!"
Nick paused. "Oh snap, I forgot to set one today!"