Rainbow lay on her bed. She kept thinking about what Pinkie had said, and, unlike a lot of the stuff she said, this made sense. That would be pretty hilarious if Rarity made her fart after all her previous disgust at it, whatever the reason.

She decided to find out.

...

The next day, Rainbow Dash called Rarity. She was wearing her usual outfit, again.

"Hey Rares, how would you like to go to the park with me?"

"That would be lovely."

...

They met at the side of a path. Rarity was wearing her usual purple skirt. No one else was around.

"So Rarity..." Rainbow began. "That's a nice necklace you got there."

"Why thank you, darling. It is quite dazzling, isn't it?"

"I was wondering... does it have any powers?"

Rarity hesitated.

"Well... as a matter of fact, it does. It can make any dirt or muck disappear. So, as long as I wear this, I won't have to worry about getting dirty because I just use its magic, and poof, I'm clean again."

"Is that all it can do?"

Rarity started to blush. "Of course. What else would it be able to do?"

"Well, yesterday, I've never farted so much even on a buttload of fart powder!"

"Are you implying that I made you break wind? You saw how appalled I was at that!" Rarity's face was redder now.

"Well, it WOULD be a pretty handy way of covering up your own farts."

"Really, I don't..."

"Fart? News flash! Everyone does! I imagine your farts are silent, but that doesn't stop the smell, so what better way to hide it than by making me fart? You know I think it's really fun, and that I take great pride in how loud I can fart! I'm not sure I can even fart silently."

"Fine! Yes, it's true! I made you fart! But only because you did the same thing to me because you have one just like it!"

"Easy, Rarity! I'm not mad. It was pretty funny, it just would have been funnier to hear you fart. Which I guess I never will. But... how did you know I didn't put fart powder in your cider?"

"Because I'm the one who gave you your magic gem!" Technically, it was Fluttershy, but she wanted to leave her out of it in case her bigger secret was discovered.

Rainbow's eyes went wide with shock. "What? But you always get so offended when Pinkie and I fart. Why would you..."

"Element of Generosity, remember? As much as I detest it, I knew you two would have fun with it. I didn't know you'd try to prank me with it."

"Sorry about that, Rarity. If I'd known... I had no idea."

"Well now you do."

"I promise I'll never prank you with it again, and I'll tell Pinkie not to either. And thanks, by the way."

"You're very welcome." Rarity gave Rainbow Dash a hug, showing that she had forgiven her. "Just... try to keep that to a minimum around me."

"So... do you even know how to fart loud?"

Rarity blushed again. "I... always keep it silent. It's the least unladylike way I can do that."

"One of these days you should try farting louder. Oh, but I won't be the one who makes you."

"I understand that's really fun for you, but it's quite different for me." Rarity's face was beet red now.

"That's fair." Rainbow didn't want to make Rarity too uncomfortable. But she noticed how much she was blushing. She suspected Rarity was already having fun with the gem's fart power.

"Have you ever used this magic on Fluttershy?" Rarity already knew the answer, for Fluttershy had never mentioned anything about the magic being used on her against her will. But, if she asked this question, then even if Rainbow Dash found out about her dirty secret, she'd never suspect Fluttershy.

"You're the only one I've ever used it on besides myself and Pinkie Pie. And even if I'd use it on Twilight, Sunset, or Applejack, I'd NEVER use it on Fluttershy. I know how sensitive she is."

"That's so sweet of you."

"And I gotta say, this thing is really cool! Aside from the fun me and Pinkie have together, from now on whenever I have to go to the bathroom, if I'm out of sight I can just go in my shorts and then use this magic to dry off."

"I have found that... I mean... Ew." Rarity feigned disgust.

"Hey, once I work the magic, it's like it never happened."

"Well... I guess it's all right. As long as you don't walk around in soiled shorts too long."

"I'll clean up as soon as I finish peeing. Or pooping."

"Ugh..." Did Rainbow suspect? Or did she just find it as fun as she did? "Well... at least you clean up right away." This was a little similar to her last comment. She didn't want to say any more, for fear she might either sound too harsh, or reveal how much fun she had wetting and soiling herself.

Rainbow chuckled a bit, deciding not to mention what she did with Pinkie Pie two days ago. It might disgust her further, and Rarity was taking this surprisingly well. "That wasn't too much, was it?"

"Not at all. I'd probably do the same thing if I wasn't too ladylike, and I wouldn't be surprised if Pinkie does it as well."

"But you gotta admit... the relief of the farts from extreme gassiness does feel really good."

"Well... I HATE to admit it, but it does. But only when I'm the only one there."

"Then... you might use the magic gem that way?"

Farting was seeming tame compared to wetting or messing, and she had just reminded her how much she loved the feeling. "To tell you the truth, I... I already have."

Rainbow's heart leapt. "I knew it!"

"Of course I have to be as ladylike as possible with it. So, don't expect me to do that in front of you. Or anyone else. Even if I do, it will be silent. And if you tell a soul, I'll smash your magic gem to pieces and make you soil yourself in front of everyone!"

"Wow, that wouldn't be very ladylike of you. But my lips are sealed! Although, if you ever feel like farting when everyone else is around... you could always use that magic on both of us. I wouldn't mind."

Rarity actually giggled a bit. "Well..." She always farted silently when she was around anyone other than Sweetie Belle or Fluttershy, and if Rainbow Dash was farting, like before, if anyone noticed a smell they'd think it was all her. "I suppose that would be fun. But remember, I will act offended and call you 'uncouth', 'revolting', 'unladylike', things like that."

"Gotchya! And if Pinkie asks, I'll tell her I used the magic gem to fart because I felt like it."

"That would be very much appreciated."

Suddenly it started pouring rain, soaking Rainbow Dash and Rarity in seconds.

Author's Notes:

Would you believe it? There's no fetish fuel in this chapter, except for reference to previous chapters or mention of possibilities. I thought I'd add a little more story to it. I haven't decided whether I should lead into Rainbow Dash and Pinkie Pie eventually finding out Rarity's dirtiest secret...