On a hot summer day in Ponyville, Rainbow Dash and Applejack had asked Twilight Sparkle, Rarity, Fluttershy, and Pinkie Pie to compete alongside them in a six-pony relay race.

Pinkie Pie entered immediately because she knew it would be fun. Twilight had never run a relay race before and was interested to try it out. Fluttershy felt confident about it as well, probably because there were five other ponies to share the spotlight with her.

Rarity wasn't usually into sports, but didn't want to let her friends down, so she agreed to enter - on the condition that they enter in style! Before the race she fashioned sparkly racing outfits for them resembling skintight shorts and matching midriff tank tops. Rarity's were purple, Twilight's were dark blue, Rainbow Dash's were a shade of blue darker than her but lighter than Twilight's outfit, Applejack's was red, Fluttershy's was green, and Pinkie Pie's was dark pink. These outfits were sporty yet lovely.

Before the race, Rarity had drank 10 cups of tea. She made her way to the racetrack, where the Main 6 would be racing against one of the other seven teams in the race first (all of which consisted mostly of background ponies). It was a hot day, so Rarity drank several bottles of water, as did Pinkie Pie and Fluttershy, while waiting half an hour for all the ponies to arrive, and the race to begin.

At the start of the race, they were positioned: Pinkie Pie, Twilight, Fluttershy, Rarity, Applejack, Rainbow Dash. As soon as the announcer - Spike - said "Go", Pinkie Pie began running, and reached Twilight before the other pony did, carrying the stick in her mouth and throwing it to her. Twilight got to Fluttershy, who got to Rarity, who ran as fast as she could.

It was a full racetrack with quite a bit of distance to cover, but Rarity reached Applejack well ahead of the other pony, and it wasn't long before Applejack and Rainbow Dash finished the race.

All of them were exhausted and a little sweaty, but satisfied that they won the race and would advance to the semifinals. They drank a lot more water while they watched the other teams race.

After the second race, Fluttershy quietly said "I'll be right back," and ran into one of the many outhouses on the racetrack.

"I really gotta pee too!" said Pinkie Pie, and she ran into another.

Now that they mentioned it, Rarity was feeling the urge to pee as well, but she brushed it off. She didn't like using public bathrooms or outhouses. She thought they were absolutely filthy from how many ponies would use them, and not knowing whether they had been cleaned properly. She'd rather hold it.

After the last two races, 20 minutes went by so the ponies could relax and be ready for the next race. Rarity fidgeted a bit, the need to pee growing heavier.

"You all right there Rares?" said Applejack.

"I'm fine," said Rarity.

After the 20 minutes, it was decided Rarity's team would, again, race first. They positioned themselves the same as last time, and raced just as well as last time.

When it was Rarity's turn, she ran faster than before, trying to hide her desperation, though the pressure in her bladder was much heavier than before.

Rarity's team won the race again. She was even hotter and sweatier than before; her outfit was damp now. The other ponies drank several bottles of water. Rarity's screaming bladder told her not to do the same, but she was very hot and thirsty, so she had no choice but to drink five bottles of water.

The Main 6 sat on the sidelines while the other two teams raced, knowing that whichever team won would be their next opponent. Rarity really needed to go, fidgeting harder now.

"I gotta go to the bathroom," said Rainbow Dash, and she ran to an outhouse. Twilight, Applejack, and Pinkie Pie each ran into another. Fluttershy was fine for the moment, she hadn't drank as much water as Pinkie Pie did. Rarity was in desperate need of a bathroom, but still wouldn't use the "filthy" outhouses.

When Rainbow Dash, Twilight, Applejack, and Pinkie returned, Applejack noticed Rarity fidgeting, and the pained look on her face.

"Ya know, if you need to go to the bathroom, why don't you just go? There's plenty of outhouses over there."

Rarity blushed. "I'm fine, thank you."

"You're gonna want to go before the next race," said Twilight. "All that water you've been drinking."

"I don't like public bathrooms, especially outhouses," said Rarity. "So filthy. Not very clean."

"So you'd rather risk wettin' yourself than use one?" said Applejack. "That wouldn't be much cleaner."

"Actually, urine is sterile," said Twilight.

"Yeah, but wetting yourself in front of HUNDREDS of ponies would be, like, the most embarrassing thing EVER!" said Pinkie Pie. "I know. I've done it once. In those cute teal shorts you made for me, Rarity."

"Oh my, I know I'd never be able to stand it," said Fluttershy.

"I can hold it," said Rarity, although she really didn't look it.

"If you say so," said Rainbow Dash. "But don't whine too much if you have an accident in your racing shorts!"

Once the race was done, there was a 30-minute wait for the next race, in which the ponies could relax, drink water, have a quick snack (nothing too big right before running), or go to the bathroom if they needed to.

Rarity began squirming even harder. She could feel the pee sloshing around inside her. By now the heat had dried the sweat off her outfit, but she was feeling very hot and thirsty again, so she couldn't help but drink more bottles of water, even though she knew she'd regret it later.

The other ponies drank more water, and Pinkie Pie ran to the bathroom twice more, while Fluttershy did so once. Rainbow Dash didn't, although she had drank nearly as much as Pinkie Pie.

"See Rarity? Even Fluttershy's not afraid to use the bathrooms here," said Twilight as soon as Fluttershy had disappeared behind the outhouse door.

As she opened her mouth to respond, Rarity accidentally farted. It was only one second long, but very loud. She blushed a little and giggled nervously. It wasn't very ladylike for a mare to fart so loudly. Rainbow Dash started laughing.

"It's not funny Rainbow Dash!" said Rarity, who had been unable to hold in her fart from focusing so hard on holding in her pee. She was embarrassed that she had done something so unladylike, but it was better than peeing herself.

The pressure grew heavier, and Rarity crossed her legs and fidgeted harder, a pained look on her face.

"Rares, just go," said Applejack. "Make a dash for one of those outhouses. I'm pretty sure they clean them every night."

Rarity considered it. She wasn't sure she could make it through the next race and then back to her home, after they claimed either their gold or silver trophy. But...

"No, I can't. Still too filthy."

Rainbow Dash chuckled at how stubborn Rarity was being. "Hey, if you wet yourself, you can always go for a swim with me in a river. Maybe a really fast raging river, that ends in a waterfall!"

Rarity was feeling more uncomfortable the longer Rainbow Dash spoke.

"Yeah, then we can splash down the waterfall together! Or, I could make it rain on you! I'll grab a big raincloud, and kick it, and there'll be lots of rain! I can almost hear the sound of raindrops already, splashing on the ground and making puddles!"

Rarity whimpered as she felt a bit of pee leak into her shorts and crossed her legs even tighter, still fidgeting.

"Rainbow, quit it!" said Applejack. "That ain't funny."

"How would you feel if you were in her position?" said Twilight.

"It's her own fault for not wanting to use the bathrooms here," said Rainbow Dash. "But... I wouldn't like it very much, so I'll stop." She considered startling Rarity into wetting herself with a thundercloud, or tickling her, but she knew Rarity and the others wouldn't like it. Except maybe Pinkie Pie, she'd just piss her own shorts from laughing too hard.

After what felt like hours for Rarity, the final race was about to begin. As Rarity stood up to go to her position, she felt herself become even more desperate from standing up. She felt like she was about to burst as she walked to her spot, which, most inconveniently for her, was the fourth spot, so she had quite a ways to walk. She sprinted the rest of the way there, hoping it wouldn't tire her out for the race. She really, REALLY needed to go, and she wasn't sure she was going to make it.

"On your marks... get set... GO!"

Rarity stood doing the pee dance while waiting for Fluttershy to reach her. She knew hundreds of ponies were watching, but didn't care. Besides, she was trusting on the pony who was running to get all the attention so no one would be looking at her until it was her turn.

Fluttershy ran faster than usual, motivated by wanting Rarity to make it to a bathroom. As soon as she reached her, she threw the stick to her.

Rarity tried to catch it in her mouth, but missed, and it fell to the ground.

"Oh, I'm so sorry Rarity," said Fluttershy.

"It's all right darling," said Rarity, trying not to sound tense. "I'm the one who missed it."

She picked up the stick and ran so fast she looked as though she could have beaten Rainbow Dash and Applejcak in a race. She needed to pee so badly that she ran faster than she ever thought she could, as if she was running toward a bathroom itself, for it was only once the race was done and they had claimed their trophy that she could get back home and use her very clean bathroom.

She reached Applejack and threw the stick to her. Applejack caught it easily, and as she ran toward Rainbow Dash, Rarity sat down, more tired than ever and dripping with sweat. She crossed her legs and fidgeted as Applejack threw the stick to Rainbow Dash, who finished the race, beating the other team by a landslide.

"Team Rainbow Dash wins!" said Spike. Rainbow Dash and Applejack had decided through hoof-wrestling who to name their team after.

Rainbow Dash, Applejack, Twilight, Fluttershy, and Pinkie Pie walked over to Rarity.

"You take your trophy," said Rarity, who was unable to keep her desperation out of her voice. "I don't think I can stand up, unless I'm running home. Tell them I'm just too tired after running so fast." Which was almost true.

The other five ponies stood on the podium to take their trophy. Rarity watched while squirming where she sat. She wished she could have been on the podium for the ponies to see her sparkly outfit in her victory, but she knew if she stood up for any reason other than to run home, she'd have an accident in front of all the ponies.

She considered making a break for it now, but she wanted to wait until the victory ceremony was over. Only ten seconds later, Rarity felt herself dribbling, and she knew she wouldn't last much longer. She decided to run back home NOW. Her friends would understand.

Before she could even stand up, however, she felt a steady stream of pee make its way out of her into her shorts, which did not let up. Rarity tried hard to stop, but she couldn't. Rarity was peeing herself, in front of hundreds of ponies. She whimpered and blushed beet red with embarrassment as her shorts grew wetter and wetter, and a puddle formed around her butt.

As she continued to wet herself, Rarity felt two things at once. The first was shock at wetting herself for the first time since, as long as she could remember. For such a popular and feminine pony such as her to pee herself like a little filly was the biggest humiliation she had ever experienced. The second feeling was relief at finally letting go, and if it wasn't so embarrassing and unladylike, part of her might have enjoyed the feeling. She even sighed in relief, against her will.

Her friends came running back toward her.

"All right Rarity, you can..." Twilight stopped at the sight of Rarity sitting in a puddle that was still growing.

"Oh my," said Fluttershy, blushing.

"Hoo, Rarity," said Applejack rather loudly. "Y'all must've been runnin' really fast to be sweatin' that much."

"Really?" said Pinkie Pie. "Cause it looks to me like she's..."

Twilight elbowed her. "We know," she whispered. "We just don't want all the other ponies to know that, so she can feel better about it."

"Oooooohhh," said Pinkie.

"I've never seen such a big puddle of sweat," said Rainbow Dash. "Way to win the race for us, Rares!"

Now that Rarity came to think about it, her sparkly purple outfit was already soaked with sweat, so only those who were really close could tell that she was peeing herself. She was sure her friends knew, but even Rainbow Dash wasn't laughing at her, and they were covering it up. Also, all the ponies had to have been looking at Rainbow Dash, Applejack, and the others because they were on the podium claiming their prize. Because of all the water she drank her pee didn't even smell so it would be easy to hide on the way back. This wasn't as bad as she had thought.

Rarity peed for about a minute and 45 seconds, and felt much better once she was done. She was still blushing lightly with embarrassment, but Applejack helped her to her feet.

"You all go on ahead," said Rainbow Dash, tossing her trophy to Applejack. "I gotta go to the bathroom."

Rainbow Dash entered one of the outhouses. Like the other ponies, her shorts were soaked with sweat too. She sat on the toilet and began peeing through her shorts into it.

"Ahhhhhhh." Rainbow Dash loved the feeling of this, and her shorts were already wet so who cares? She let out a loud fart and giggled.