Author's Notes:

Done by request. I know Part 2 seems a bit stretchy but it was in the request, and has an explanation. (Also will ignore the fat chapter, we'll say that's an alt. universe)

In this chapter, Sunset is wearing a yellow shirt and her Legend of Everfree shorts, and Fluttershy is wearing her usual white tank top and green skirt.

Sunset Shimmer and Fluttershy were eating breakfast at a restaurant one morning.

"Do these eggs taste undercooked to you?" said Fluttershy.

"A little," said Sunset.

Once they were done, Sunset paid the bill and they went to a coffee shop to get something to drink. Fluttershy paid for the drinks this time.

They went for a walk in the park while drinking their coffee, enjoying the weather and the sights in the park, and in Fluttershy's case, the birds, rabbits, and squirrels that could be seen, or the dogs that people were walking.

Suddenly, Sunset was hit with an uncomfortable feeling. She turned towards Fluttershy.

Fluttershy was also feeling very uncomfortable. The undercooked eggs and prune juice had caught up with her as well. She looked at Sunset and blushed lightly, but could tell that Sunset had to go as badly as she did.

They ran towards the outhouse.

"You go first," said Sunset as they ran. "I can hold it."

"I... I hope so." Fluttershy didn't want to risk Sunset messing herself but Sunset was offering and she'd be really embarrassed if she didn't make it.

They reached the outhouse, and saw the dreaded Out of Order sign on it.

"Now what do we do?" said Fluttershy, fidgeting where she stood as she let out a silent fart, terrified that she might soil her panties in front of her friend.

"We find a bush to go behind," said Sunset.

They ran around the park, letting out a few wet farts as they ran, while their desperation increased.

"I don't think I'm gonna make it," whimpered Fluttershy.

"Hold on for just a few more seconds," said Sunset as she changed direction. Running alongside her Fluttershy saw the bushes they were headed towards. She held it in as best she could.

Sunset let out another wet fart and quickly put her hand on her butt, relieved that although it felt a little wet, there was no mess in her shorts.

They stopped at the bush. Both were very desperate at this point.

"You go first," said Sunset.

"No, you go first," said Fluttershy. "I don't think you can hold it any longer."

"Neither can you. I insist."

They both felt the pressure increase, and they knew they were seconds away from messing themselves. Without a second thought, they both ran behind the bush together. Sunset pulled her shorts and white panties down, Fluttershy hiked up her skirt and pulled her pink panties down, and they noisily released the contents of their bowels.

Diarrhea exploded out of both their rears onto the grass below.

Sunset and Fluttershy sighed in relief. They looked at each other and blushed with embarrassment, but as they were in the same position they didn't feel too ashamed.

"Wow, you really needed to go," said Fluttershy, trying to make light of the situation.

"Good thing we made it to the bushes," said Sunset. "Or else our underwear would be damaged beyond repair."

Fluttershy giggled a little, still blushing lightly and feeling much better from the relief, as well as not soiling herself.

Finally they both finished. A big, stinky pile of diarrhea lay behind them as they stood up. Sunset pulled her shorts back up, and Fluttershy pulled her panties back up.

As they continued their walk, their underwear felt a little wet and dirty, due to their diarrhea and not getting a chance to wipe. But, they were just relieved that that was as dirty as they got, and that they had avoided a humiliating and messy accident. They scratched their butts a bit before they decided to go home and clean up.

...

The next day, Sunset and Fluttershy were going on a roadtrip. They were wearing their same outfits, though different underwear. Today Sunset's panties were black and Fluttershy's were green. Sunset was driving.

They were talking about all the animals they'd look at at the zoo, when suddenly they were both hit with another intense urge to poop, for they had eaten a big meal last night and this morning they drank milk that may have been past the expiration date.

Fluttershy whimpered, too shy to say how badly she needed to go. But she didn't have to.

Sunset groaned and let out a loud, wet fart. "Ugh, I really need to stop and find a bathroom." She looked sideways at Fluttershy. "Both of us, it seems."

Fluttershy blushed, but was grateful that they were going to stop soon.

"Where's the nearest gas station?" said Fluttershy as she fidgeted in her seat.

"Not for another half hour," said Sunset, also fidgeting. "But I think there's an outhouse in 15 minutes."

"I don't know if I can hold it that long..." Fluttershy let out a loud fart, and blushed profusely. "Oh... Excuse me..."

"It's all right." Sunset farted again. "I know you couldn't help it. But maybe I should do this." She opened the windows so the car wasn't full of the fart smell.

As the minutes went by, Sunset and Fluttershy became more desperate, and their farts grew wetter and stinkier. The pressure became more intense than last time.

"We might have to use the outhouse," said Sunset about 14 minutes into their desperation. "I don't think I can hold it another 16 minutes."

Fluttershy let out a sloppy wet fart. "Uh-oh..." She felt her butt under her skirt. Her panties did feel a little wet and dirty but there was no mess in them, and she sighed in relief. Until she felt the pressure increase, and she knew it wasn't going to be a fart next time.

Finally, they reached the outhouse. It was in a desert area with no trees or bushes. Once stopped on the side of the road, they fumbled with their seat belts, undoing them and rushing to the outhouse. To their immense relief, they did not see an "Out of Order" sign on it.

"You go first," said Sunset.

Fluttershy was grateful, but was afraid Sunset wouldn't make it. "Are... are you sure?" She felt the pressure in her bowels increase and fidgeted.

"I insist. I'll go behind the outhouse if I feel I can't hold it."

"All right."

Fluttershy ran into the outhouse, closing and locking the door behind her.

A few seconds later, Sunset could hear loud farts from inside the outhouse, and a sigh of relief. She held it for about five seconds into this, but then the pressure became too much for her. So she ran behind the outhouse, pulled her shorts and underwear down, and let go.

Hyperscat cascaded out of her butt and onto the sand below her. She sighed in relief, and looked around, equally relieved that no one could see her in this position.

She had really needed to go, for after a few minutes it wouldn't stop.

Inside, Fluttershy's torrent of hyperscat wouldn't stop either. She was thankful this was the kind of outhouse with a hole rather than a regular toilet, or else it would have overflowed by now.

Soon Sunset had to move, for her pile of shit was getting close to her butt and she STILL hadn't stopped. There was no doubt about it - she had Megahyperscat again, and, judging from the continued sounds of farts inside, so did Fluttershy.

After a whopping 15 minutes, she was finished. Even last time she got Megahyperscat she had never pooped non-stop for this long before, and did not believe such a thing was possible even in Equestria. She pulled her shorts back up and looked at the big mess she had made on the sand. She blushed knowing someone would probably find it sooner or later, but at least she wouldn't suffer the humiliation of anyone knowing it was her.

Fluttershy finished around the same time. She felt very relieved, more so than last time; that she no longer needed to go, that she had finally finished after an unnaturally long time, and that it hadn't ended up overflowing her panties in what would have been the most humiliating accident ever. She was a little nervous about why it had taken so long, but she suspected she knew the answer to that.

As Sunset walked to the outhouse door, intending to use its toilet paper, Fluttershy walked out, looking relieved.

"How did it go?" said Sunset.

"I just made it," said Fluttershy. "But there wasn't a lot of toilet paper left, and... it wasn't enough." She blushed and scratched her butt a little.

"That's all right," said Sunset. "I'm just glad we didn't mess ourselves."

"What about you?"

"I had to go behind the outhouse, but I made it too."

"That's good. But it's never taken that long to finish before..."

"We've got Megahyperscat. Like that time when I soiled myself in school." She blushed lightly remembering this, but was over it by now. "I'll write to Princess Twilight and ask for the cure."

They got back into the car and continued their trip. Aside from their underwear being dirty, the rest of the trip went without a hitch. The day's Megahyperscat had affected them at once this time, and wasn't a problem again before Princess Twilight arrived with the antidote.