Carousel boutique was teeming with custom.
This was by far the busiest day Rarity had seen all season, and even the summer heat beating down on Ponyville was not enough to stop the town’s fashion-minded citizens from flocking to the flash sale. Rarity, in her generous nature, was offering 50% off all orders of two or more items, and ponies showed up in their dozens to take their pick from her extensive collection.

The line outside stretched all the way into the center of town. It seemed that everypony (besides Rainbow Dash and Applejack) were here. An event so popular had of course roused the attention of more than just patrons. Hoity Toity himself was in attendance, pacing around the crowded boutique and regarding its customers with a haughty expression.
Rarity, however, was in distress. It was all her fault, really. In order to ensue her event was well-catered, she had paid for a cadre of royal chefs from the very kitchen of Celestia herself. Their hors d’oeuvres were sublime. A varied spread of spiced vegetable platters, cheese vol au vants and enough sweets and deserts to give Pinkie Pie a toothache. Rarity was never usually a greedy pony, but with the elegant nibbles floating around on serving dishes all day she hadn’t been able to help herself. And the result now was a grumbling tummy and a growing need. A need so perverse and uncouth that Rarity dared not even think about it.
She had to pass gas.

At first she had mistaken the cramps for hunger, and foolishly stuffed her face with more snacks in an effort to stifle her stomach noises. It was obvious to her now that she had to release some fumes, and fast. The pressure mounting in her lower gut had developed from annoying to painful. But as she struggled through the ocean of ponies on the boutique floor, she realized this would not be as easy as she had first thought. Desperate times called for desperate measures, and in this instance those desperate measures came in the form of small, imperceptibly silent farts. Rarity’s hefty dress was fortunately just thick and suffocating enough that it smothered the sound of flatulence, and most of the smell.

But she was still sure to let them ruffle out of her at the most opportune moments. A few ponies wondered why she kept circling round to stand by the cheese board with a focused look on her face. While this method of puffing out little farts had been working so far, Rarity knew it wouldn’t be enough. Her stomach was stirring up flatus faster than she could pump it out this way, and a riotous growl from deep in her belly was the final straw.
She had to get to her office.

It was all the way on the other side of the room, but she was determined. She was threading through the crowd, showering them with apologies (and a few steamy farts). Only a few meters away. Her belly was brewing up a big one. The kind so huge she knew her fabric wouldn’t cover the sound nor the smell.
And that’s when a pony leapt out in front of her.

The fright almost made her empty her load then and there, but with a whimper and a lip-bite she managed to keep her cool.

”Rarity! Ohmygosh your summer line is, like, wow! Like, the words to describe it just, like, totally escape me!” 

”Wh-Why thank you, my dear! I... puh-put many hours into its design.”
She was losing composure and it was plain to see. In a brazen move, she decided to let some more air out of her bloated stomach. Slowly.
She gave a gentle push. 

The low, inaudible rumble and the warmth broiling into her dress were the only signs she was breaking wind at all. It was working so well that Rarity got cocky, and pushed a bit harder. Big mistake.
What started out silent quickly grew in volume, until the gas was roaring from the pony’s back end with a sound like ripping paper. Her face was still and shocked, but now that the flow had started it wouldn’t stop. The ponies all looked around in utter disbelief as Rarity unloaded fifteen full seconds of cheek-wobbling fury. The pressure finally spiked and a second ripping sound joined the first. 
The noise of Rarity’s dress splitting down the middle. Her pillowy cheeks spilled out through the split, and now unrestrained they fumed their atrocious cabbage-like stink into the busy room.

Rarity’s fart spluttered to an end, finishing off with one last humiliating squeak. The room was absolutely silent. Even the band had stopped playing their stringed instruments (although this was mostly to cover their noses) The plague of digested cheese, fermented fungi and rancid broccoli spread to every inch of the boutique.

"A-Aha..." Rarity started, laughing nervously to ease the tension.
She politely fanned her hoof in front of her face, as if it would make any impact on the thoroughly fumigated shop floor.
”Excuse moi?” 