The next day was Monday. Sunset, Rainbow Dash, and Rarity wished it was raining today so they'd be able to pee without anyone at school noticing. They told anyone who noticed the brown spots on their butts that they had slipped and fallen in the mud. Some of them, like Trixie, didn't seem to be buying it.

At lunch, they needed to pee, so they ran to the showers, turned them on, and peed while under the shower water.

"I just felt really dirty so I hit the showers," said Rarity, giggling nervously whenever anyone noticed she was soaking wet.

"It's pretty hot so I needed to cool down," said Sunset.

"It's so hot I'm sweating a lake!" said Rainbow Dash. She had been just as soaked with sweat before, after all.

They managed to conceal their predicament from Twilight, Applejack, Fluttershy, and Pinkie Pie for a while, though they were sure Pinkie could tell what was really going on. Although, with how often they were wetting and messing themselves, they slowly started to smell bad even with their showers.

Then, on Friday, they ate some bad fries at the cafeteria and ended up soiling themselves in the middle of the final class (after a very gassy first half). Everyone else laughed at them except Twilight, Fluttershy, and Applejack, much to their embarrassment.

...

On Saturday, it had been a week since they had been cursed. After they took their morning pee in their shorts/jeans, they heard a knock on Rarity's door, and opened it to find Twilight Sparkle in the doorway.

"I hope this isn't a bad time," said Twilight, pausing to sniff the scent in the air, "but... I know you didn't just soil yourselves in class. Something's been up for a while."

"The sirens got some new magical gems and cursed us with a spell that makes us unable to undress," said Sunset.

"So we're peeing and pooping ourselves all the time," said Rainbow Dash. Rarity blushed.

"Do you know of any way to break the spell?" said Twilight.

"No, but... hold on!" said Sunset. "Aria said she tested it on Sonata. But Sonata looked pretty dry and clean to me."

"A second dose of that gem must reverse the effects!"

"But how are we going to make that happen?"

"I've got an idea."

...

The sirens were sitting on a bench, still laughing at what they had done, when Applejack, Fluttershy, and Pinkie Pie walked by.

"Hey, let's get revenge on them too," said Adagio, and they stood up and tiptoed after them.

Adagio was wearing a purple sweater and jeans, Aria was wearing her usual purple jeans with a white tank top and green vest, and Sonata was wearing skintight pink shorts with a dark pink tank top.

The three girls stopped at the edge of a river near a tree. They stood still, admiring the sight of the river and the trees across it.

"Revenge is ours!" said the sirens, and they each shot a bolt of magic at the unsuspecting girls.

Sunset, Rainbow, and Rarity jumped out from behind the trees into the path of the magic. The beams hit them, and there was a flash of light.

"No!" said Aria. "This was a trap?"

"Ooooh, sneaky!" said Sonata.

Twilight stood several feet behind the sirens, and pressed a button on a projector she was carrying. Applejack, Fluttershy, and Pinkie Pie disappeared. They were holograms.

Rainbow shamelessly pulled her wet and dirty shorts down. "Yes! It worked! The spell is broken!" She pulled them up and started to pee. "Ahhhhhh..."

Rarity rolled her eyes, but giggled slightly, partly out of relief that she wasn't going to wet herself again.

"So what if you broke our spell?" said Adagio. "We'll just cast it again!" She, Aria, and Sonata raised their gems and fired.

Rarity activated her force field. The magic bolts rebounded off the barrier and hit the sirens. The three sirens squealed in surprise and fell on their butts - and as they did, their gems flew out of their hands and into the river.

"No..."

Sonata giggled while Adagio looked very nervous.

"No no no no no!"

Aria jumped into the river and searched for the gems, but there was no sign of them. The river had washed them away. Aria climbed out of the water.

Sonata tried to pull her pink shorts down. "Nope! They're not coming off!"

"You idiot!" said Aria, who was dripping wet. "Do you realize what this means?"

"We do!" said Rarity. "And it serves you right!"

"Let's get out of here," said Adagio, and the sirens ran. Sonata leaving a trail of pee behind her.

"Well, that's done now," said Sunset.

"For us, anyway!" said Rainbow Dash. "And it wasn't so bad!" She was planning on wetting and messing herself as often as she could at home.

"Now, it's time to take the most glorious shower of our lives," said Rarity. "First let's get a change of clothes."

And they were sure going to have fun catching the sirens' new situation on camera and showing it to everyone to humiliate them further!

Author's Note

I threw in the last sentence later by request.

And yes, I know the first half is a little rushed. I just wanted to get to the last part and was already descriptive enough about everything in the first three chapters, plus the reasons I say below.