Rarity looked back and saw Twilight coming over with the ruler, she grinned. "I assume that will be the instrument you will be using for the 'testing'?"

"That's correct. It should provide ample damage to your buttocks. This particular item is well known for leaving quite a mark." Twilight revealed.

"I bet it does." Rarity said with a giggle.

"Do you know how long it takes to clean that window, and then you come along and press your buttocks against it?" Twilight asked, putting on the voice of an authority figure about to discipline her student. "Such a naughty student, mooning your teacher like that. What do you have to say for yourself?"

"Uh… sorry?" Rarity responded with a cheeky grin.

"You don't look sorry." Twilight stated, holding in a laugh.

"I thought it was pretty funny." Rarity stated, smirking again. "Also, that window felt absolutely wonderful against my big... fat… derriere."

She rubbed it in by wiggling her massive tush in Twilight's face, taunting her.

"If you are not sorry… then you shall be punished!" Twilight declared as she put one hand on Rarity's back and raised the other one holding the ruler above her head. "Count them for me. We'll stop when your tushie turns red. Only look towards the clock, not back at me."

Rarity still grinned mischievously. "Whatever you say dearie, I do feel bad for when you have to clean that window later. After all, my backside certainly left quite the impression so to speak." The fashionista teased her further.

But before she could tease any more she heard the swooshing sound the ruler made as it came down and gave her a sharp, wooden smack to the rear. She yelped while her twin orbs jiggled and shook.

"Count them." Twilight told her, firmly. "And if you lose count we'll start over again."

"Ooh… one." Rarity finally said.

Twilight lifted the ruler back above her head and brought it back down onto the fashionista's rear. A loud resounding crack echoed once the ruler made contact with the flesh.

"Ah! Two." Rarity yelped a little, looking back to see a faint pink mark where the ruler hit her tush.

"Think about what you did." Twilight said sternly, raising the ruler and swinging it down unforgivingly onto her friend's bare buttocks, making the fashionista cry out and jump.

"AH! Three!" Rarity was starting to shake, which made her rear end wobble from side to side.

"Ask yourself, was it worth it?" Twilight told Rarity, giving her butt another swift smack with the ruler.

"GAH! F-four!" The purple haired girl stammered, both from the shock of the pain and the arousement she was getting out of this. Her rear end was now noticeably pink, but that still wasn't enough.

Smack!

"Eep! Five!"

Smack!

"Gah! Ow… Six!"

Smack!

"My Goodness! Seven!"

Smack!

"AH! Ow! Eight!"

Smack!

"Nine! Oh… please…!"

Rarity bit her lip, letting out a whimper as the surprisingly painful spanking continued. She felt tears in her eyes, a flush of embarrassment rising to her cheeks, wincing as another blow landed on her increasingly sore behind before she counted it out loud. Each hit sent a little spike of pain through her, and it worsened with each and every blow.

As she spanked Rarity, Twilight felt an intense rush every time her ruler smacked Rarity's cheeks and slowly turned them red, the sound of it echoing through the lab. She liked watching how the flesh of her friend's butt cheeks jiggled all over each time she smacked them. Eventually her arm got tired, causing her to stop.

"Tell me…. Have you learned your lesson yet?" Twilight asked, lightly brushing the ruler along Rarity's bright red butt, making her friend wince from the sting.

"Y-Y-Yes…" Rarity finally said while Twilight took out her notebook and wrote down new information.

"Interesting… we reached twenty-six spanks, and it only took… twelve minutes for your rear to become red and bruised," she remarked.

"Ooh, you hit pretty hard." Rarity told her friend while rubbing her sore tush as she stood up straight.

"Oh! Sorry!" Sci-Twi cringed, her meek self now returning.

"No, no, it's ok, I asked you too, and it was… oh… part of the tests, correct?" Rarity reminded.

"Oh yes! Part of the tests." Twilight repeated, smiling cheekily. The fashionista still rubbed her now reddened buttocks affectionately.

"Ow, this stings almost as much as that one time…" Rarity noticed.

Twilight's ears perked up curiously. "That one time?"

"Oh, don't you recall? I told everyone I spanked myself after I… ahem… mooned the store I didn't like…" Rarity reminded.

"Oh yeah… and how did you cool them off?" Sci-Twi inquired.

"Well… we… kind of already did it… on your window…" Rarity confessed, blushing.

"Oh… Well, you can do that again if it'll help you. Also, you could try sitting on the desks, they get pretty chilly." Twilight told her.

"Thank you, dearie." Rarity smiled, hopping onto one of the desks, shivering and confirming the coldness of the desks surface. "Oh, this feels sooo good right now."

The purple haired girl grinned, wiggling her seated tush on the surface of the desk.

"I didn't know you enjoyed pain so much…." Twilight said.

"It's pain done too much to my derriere that… How do you say it?" Rarity trailed off.

"Arouses you?" Twilight suggested.

"Yes! That is it!" Rarity confirmed.

"I… think you're not just an exhibitionist… but a masochist as well." Twilight observed.

"Oh, well, I suppose I am… who knew?" Rarity shrugged.

"Do you know when you started getting aroused by it?" Twilight inquired, fascinated.

"Well… I only just recently really started getting into it. Although, I do remember a time I had a particularly painful encounter with a wasp. Left my lovely derriere sore for a couple days." Rarity revealed,

"Oh? I didn't know that." Twilight remarked.

"Yes… not something I enjoy telling… for obvious reasons." The white skinned girl admitted. "It's a shame though…"

"What is?" Twilight asked.

"Well, after this is done I have to return to acting prim and proper, which is still part of who I am mind you, but I just feel…" Rarity began.

"Like you want to express your naughtiness without being judged?" The nerdy girl guessed.

"Correct! And not just with you or Rainbow Dash, Applejack and Pinkie Pie but all of the girls, maybe even everyone but… that is quite unlikely…" Rarity sighed.

Twilight gave her friend a sympathetic smile, taking a seat on a desk next to her's.

"I understand. And… To be honest, I enjoyed doing a lot of those tests with you." Twilight admitted, blushing. "I got to see a part of myself that I… didn't know existed. And learn quite a bit about butts."

"Such as?"

"Well, both our 'derrieres' are quite large in size both due to the combination of fat and muscle, which is both a comfort and a hazard?"

"Oh?"

"Yes. See while they can cushion are falls if we trip they're also quite sensitive to pain and tend to involuntarily… jiggle a lot."

Rarity smiled and giggled. "It looks like we both learned quite a bit about our own posteriors as well."

Twilight giggled as well. "Yeah, you're right." She looked down and fiddled with her fingers a little. "If you don't mind me asking you. How did that wasp end up stinging your butt?" Twilight asked, blushing.

"Oh, that?" Rarity asked. "Easy, I saw a penny, bent over to pick it up, just as a wasp flew by. It thought my rump was a target and stung it! For no reason!"

"Ooh…" Twilight cringed.

"That's what I said!" Rarity stated.

"That sounds painful. I've had something sort of similar happen." Twilight confessed.

"Oh?" Rarity asked, interested.

"Yeah… I… kinda did an experiment designed to attract and control bees, like a mechanical queen… but it… backfired."

"Backfired? How?"

"They… chased me… for a while."

"Oh dear…"

"Yes… I hid in a bush, but I got stuck in it with my rump sticking in air as well and… well you can imagine what the bees did when they saw it."

"Oh, I am so sorry." Rarity said, sympathetically.

"It's ok… though I couldn't leave the house for a week after that… or sit for that matter." Twilight confessed.

"Oh my, I can't possibly imagine getting stung like that repeatedly, by multiple bees nonetheless." The fashionista shuddered at just the thought of it.

"Bees aren't the only thing that's left my behind feeling sore. Ever heard of stinging nettle?" Twilight asked.

"Stinging nettle?" Rarity echoed, confused.

"It's a type of plant you do not want touching your skin. It can leave a stinging sensation behind if you touch it, which is why they called it that."

Rarity winced again at the description of it. "Ooh, how in the world did you get that to touch your bottom?"

Twilight blushed once again. "I was little… and careless… it's a long story."

"Duly noted." Rarity nodded, deciding to take her word for it.

"Although not as bad as something like poison ivy."

"My goodness! How much torment has your poor derriere taken?"

"More then I care to admit…"

"Hmm…" Rarity muttered, gaining an interesting thought.

"What?" Sci-Twi asked.

"Tell me dear… I know you have a small… 'attraction' to Timber Spruce… but… based on your actions and expressions… do you have an interest in girls as well?" Rarity questioned.

"Uh… well…" Twilight stuttered.

"Because to be honest… I might too…" Rarity confessed after a loud gulp.

Both of them were quiet for a moment, blushing awkwardly as they looked around.

"Maybe just a little bit…." Twilight admitted.

"Anyone I know?" Rarity inquired.

"No… actually… I'm not looking for anything… exclusive… mainly… I'd like to do more of what… we did… but with other girls." Twilight confessed, blushing like crazy.

"I see… well that would be quite ideal… one is less shy about one's body when around other females and we could play with and complement each other's behinds." Rarity realized.

"Right and I think we both agree that the butt… is the best part of a girl's body." Twilight stated.

"Oh yes, and even though I cursed myself quite a lot for these wide hips, I can't help but be appreciative of them as well."

"Well, like Rainbow would say, the bigger it is, the more you bring to the window."

"That goes without saying."

"And Applejack says guys like girls with 'big fat porches'."

"And girls." Rarity giggled.

Twilight blushed yet couldn't help but giggle. "Yeah, girls too…."

Rarity suddenly giggled again, gaining the science girl's attention.

"What's so funny?" She inquired.

"Oh nothing. Just imagining you mooning Timber." The fashionista teased. If Twilight wasn't already red in the face, she was now.

"Oh you!" Twilight said, grinning and rolling her eyes. "Speaking of mooning, who are some others we would moon?"

"Good question…" Rarity muttered as she started to think.

"Well, I remember pretending you were Cinch earlier, and that made it easier to moon you." Twilight started. "So, I'm curious to see who else I would moon."

"Do you mean… for real?" Rarity asked, interested.

"Well….I'm not sure I'll ever actually moon someone." Twilight stated. "If it was someone I'll never see again, then just maybe…"

Rarity smirked over at her friend, who was blushing madly. "Ooh, looks like you have some naughty thoughts as well."

"Yeah… guess I do…" Twilight admitted.

"So….Have anyone in mind?" Rarity asked, grinning eagerly.

Twilight looked over at her friend, wide eyed and surprised. "Wait, you mean for real?"

"No, well… depends on if you would want to." Rarity told her.

"Hmm…" Twilight began. "There is this one group that I personally find pretty annoying."

"Oh? Do tell." The fashionista said, her eyes wide with curiosity.

"There's this planetarium a little bit outside of town, up on a mountain. Once a month they host a group event where other people interested in astronomy, like myself, can go and look through the giant telescope. We also talk about all sorts of space related things, such as new discoveries and planned missions, etc."

"Oh, that sounds like a nice group. They don't sound bothersome at all."

"I wasn't talking about that group, I meant another group."

"Ooh?" Rarity cooed, really getting interested.

"Well, you see, the planetarium is a little far away. So understandably, I, and some other people, catch a bus to take us up the mountainside. While on the drive up the mountain, there's always this one group of people, who do nothing but stand on the side of the road, protesting for the removal of the planetarium."

"Oh dear…." Rarity said, a little surprised. "Why do they want it gone?"

"Oh, this is what really ticks me off." The science girl said, getting visibly heated up at just the mere mention of them. "They want the planetarium gone, just because they believe space is some big conspiracy, and that it's a waste of money!"

"Oh my word. That's pretty shortsighted of them." Rarity remarked, stunned.

"You're telling me? They are absolutely insane!" Twilight yelled out, fuming with anger. "Look, I can respect others' opinions, even if they are ridiculous. But this group wants to ruin it for me, and everyone else actually interested in astronomy, just because they themselves don't think space is real."

"I can certainly see now why you'd be so upset about that." Rarity sympathized, noticing how frustrated this made her friend.

"I'm sorry that I sound so angry, it's just…. Ugh! Those kinds of people make me so mad." Twilight said, pushing her glasses back up.

"Mad enough to moon them?" Rarity asked with a raised brow.

"Maybe…" Twilight mused. A corner of her lip curled into a grin. "That does sound really tempting."

"So…? You interested in doing it for real?" Rarity questioned, grinning mischievously.

"Well… it would be a great scientific exploration…" Sci-Twi reasoned.

"Quite right." Rarity nodded. "So, when is your next group event taking place?"

"Oh, it's actually tomorrow. We'll be observing the full moon through the telescope." Twilight answered.

Rarity giggled. "There's a joke there I could say… but it's far too easy!"

"Ooh, I see what you mean." Twilight nudged Rarity's side, giggling along with her.

"So, how would you go about… mooning them?" Rarity inquired, grinning devilishly.

"Well, the bus passes by them each time we go up the mountain, so it'll probably be when the bus passes by them." Twilight told her.

"Just like Rainbow and the Crystal Prep students…" Rarity realized.

"Yes and… would it be too much to ask if you… came along with me?" Sci-Twi requested.

"Oh, absolutely dearie. If it'll make you feel more comfortable to be around a friend." Rarity smiled comfortingly.

"Thank you… It means a lot to me that'd you would come along for this." Twilight smiled back, grateful to have such an understanding friend, as well as share some similar interests with her.

"Then it's settled then." Rarity declared as she held out a hand. "If it's a moon they want, then it is a moon they shall get!"

Twilight giggled and met with Rarity's hand, shaking it. "Looks like there will be two full moons out tomorrow."

"Looks like!" Rarity beamed.

And with that, their plan to moon another group of people was set in motion.

Next Chapter: Chapter 12 Estimated time remaining: 4 Hours, 10 Minutes