"But I said I was sorry!"

Sweetie Belle waddled beside Rarity, her rear being pushed forward by her sister's magic as they walked down the street. "Can we at least slow down?" she whined, "My boobies are getting heavy..." Her massive breasts had swollen up even further, her teats nearly touching the ground while her legs were spread apart . "Please?"

"Absolutely not." Rarity said, without turning around.

"Please?"

"No."

Sweetie Belle made more little whiny noises, occasionally reaching back with her forehooves and holding her bosoms. A few minutes later, she suddenly made a loud squeak and plopped down to the ground. Rarity sighed. "What is it now?" she asked, looking back at her sister.

"I-I think m-more milk is-is coming..." Sweetie Belle moaned, wrapping her forelegs around her breasts and squeezing them, "Ooooh...." Slowly, they started inching out, while Sweetie Belle pushed downwards with her hips into the ground. "P-please...j-just give ME a second..." A big smile came on her face, her eyes half closing, and she began making little squeaks of pleasure. "Sis, c-could you do me a favor?" she asked, looking towards her sister.

"Oh my word, Sweetie Belle!" Rarity yelled, lighting up her horn and yanking her sister towards her, "We're in public!"

"Ooh, you're right!" Sweetie Belle said, taking a break from massaging her breasts, "Hey, does anypony have a bucket? I REALLY need to be milked right now!"

Rarity shoved a hoof over Sweetie Belle's mouth, ears perking up and listening as the sound echoed. "Sweetie Belle, what do you think you're doing?!" she hissed, "Do you want everypony in Ponyville to know?"

"Well, yeah!" Sweetie Belle said, pausing from rubbing her boobs, "I can give out more milk if more ponies know, duh!" She then returned to happily nuzzling her bosoms.

Rarity's expression went flat, kind of like she was getting tired of all this stupid crap. She lit up her horn and pulled Sweetie Belle's forehoof, then continued walking down the road. Sweetie, however, fumbled around on the ground, trying to walk normally. "Slow down, Rarity! You're hurting me!" she whined, clutching her boobs with a foreleg while they dragged along the ground, quickly trying to waddle alongside her sister.

Rarity did not slow down, but instead continued until they arrived at Twilight's castle, where she released Sweetie's hoof and let her roll backwards onto her breasts. "Twilight, darling, are you home?" she called, opening the door and coming inside, "I have a problem that I need some help with!"

"Why, thank you!" Sweetie Belle squeaked happily behind her, "But where's your bucket?" Rarity span around and saw a stallion leaning down, grasping Sweetie Belle's breasts and pressing his mouth against her teat. "Ooooh! T-that's fine too!"

Quick as lightning, Rarity leaped and kicked the stallion in the face, successfully destroying his dreams of drinking milk from Sweetie Belle's massive titties. It also crushed his jaw, but that wasn't important. Rarity yanked her sister inside the castle and slammed the door in his face. "Sweetie, what were you thinking?!" she yelled.

"I need to be milked, and he offered!" Sweetie Belle replied, holding her breasts indignantly.

"Sweetie, he wasn't milking you to help you," Rarity said, putting her hoof on her shoulder, "He was trying to help himself."

Sweetie Belle looked thoughtful, then made a huge grin. "Cheerilee told us about that in class! It's called, um...Mutualism!" she squeaked, "That's so cool!"

Rarity closed her eyes and lowered her head, taking a deep breath and letting it out. Then, she made a big smile. "Twilight!" she called in an overly happy tone, "Are you home?"

"Yeah, yeah!" a voice called back, "Just a sec, woo!" Twilight stumbled out of a nearby room, eyes half open with a silly smile. "Oh, Rarity, what's up?"

Rarity looked confused. Sweetie Belle was curious as well, but was too busy holding her bosoms to pay much attention. "Twilight, are you alright, darling?" Rarity asked, "You seem...out of it..."

"Nah, girl!" Twilight shouted, "I'm just sooooo excited! To be working on this cool potion in this room, come check it out!" She stumbled back into the room, making a loud sniffing noise as soon as she entered. Rarity and Sweetie Belle looked at each other, then followed behind her. "Check it," Twilight said, coolly pointing to a big cauldron in the middle of the room, "That stuff's gonna rock when it's done."

"My, my, what a lovely-scent!" Rarity suddenly crinkled her face, "My word, Twilight, that smells horrible!"

Sweetie Belle sniffed, then smiled. "I kinda like it," she said.

"No, you don't," Rarity replied, flatly.

"It starts smelling better after a while. Anyway, what'sit that you're wanting?" Twilight slurred, "This is kinda a big deal, yo." She turned and noticed Sweetie Belle sitting next to Rarity. "Hey, yo, Sweetie Belle! Good to see you, girl!" she said, walking over and wrapping her hoof around her back. She looked down, and then started staring curiously at Sweetie's massive boobs. "Yo Rares, what happened here? Puberty?" she asked, pointing to the aforementioned huge boobies.

"Those are-

"I'm a milkmare, now!" Sweetie Belle squeaked, "I'm making milk!"

"Dang Sweetie!" Twilight said, whistling, "Tha'ss nice!"

Rarity's face was currently having a meeting with her hoof, but after it ended she trotted up to her friend. "Twilight, maybe you should invest in some sort of filter. I think your potion has some fumes..." she said politely.

"Nah, girl, it'sall good!" Twilight said, adding a little wave with her hoof. Suddenly, they were distracted by a noise coming from the closet. "Oh, that's just Spike, he's playing with his favorite sock in there," she said, nodding her head for no good reason.

"His favorite sock?" Rarity asked, very discomforted, then shook it off, "Never mind, I don't want to know." She looked at Twilight, who looked back with half open, very reddened eyes. "Do you have any books about...mammary potions?"

"Mammary potions?" Twilight asked, flopping over lazily onto Sweetie Belle's huge boobs, "You mean like potions for titties?" Rarity pulled her friend back to her hooves with her magic and made her face her directly. "Like, there's an encyclopedia about boobies around here, somewhere..." she mumbled, then started giggling, "Heh, boobies..."

"Right," Rarity sighed, "and where is this boob encyclopedia?"

"I have it!" Spike called, opening the door, "And it's actually named Booblopedia, Everything You Wanted To Know About Boobies, So You Bought a Book About Them: 24th Edition." He held the book aloft, then suddenly was distracted by something behind Rarity. "Whoa..." he murmured, "Twilight, can you do whatever you did to Sweetie Belle on Rarity?"

"What? What is it nooooowaugh!" Rarity said, her face turning horrified partway through her sentence as she turned around.

Sweetie Belle was on the floor, her face bright red, rolled over onto one of her huge breasts, sucking harshly at her big teats. The other breast was gushing out milk all over the floor, with her hoof meekly held over it, failing to stop the leakage. "Mmmm..." she moaned, her little hips swaying forward and back as her mouth filled with the white fluid.

"Sweetie Belle! What in Tartarus are you doing!?" Rarity screamed, zooming over to her little sister.

Sweetie Belle's eyes rolled up to look at her, pure bliss running all over her face. Or maybe that was the milk that was gushing all over her. "I told you I needed to be milked, Rarity!" she said, momentarily removing her mouth and being sprayed with milk, "Can you get the other one, please?" She stuck her mouth back around her teat and began suckling again, squeezing down on her soft breast with her hoof.

"Absolutely not!" Rarity said, her face frozen in a horrified state. She looked around, desperately as the puddle underneath Sweetie Belle began to move outwards from her little body. "Twilight!" Rarity said, suddenly grabbing her friend in her hooves, "Do something!"

Twilight blinked, looking around the room sleepily, then stood up and stumbled towards Sweetie Belle. "Hm..." she murmured. Then, she leaned down and latched her mouth onto Sweetie Belle's other teat, suckling and wrapping her hooves around the giant breast. "Mmm! Sweetie, your milk is awesome!" she said, pulling away for a second before returning immediately. Rarity managed to drop her jaw an impressively far distance towards the ground.

"Hey, I wanna help, too!" Spike said, running past Rarity to get to Sweetie Belle, "Can I?" Sweetie Belle, blushing, took her mouth off of her nipple and grinned widely with her mouth hanging open. Milk began splattering all over her fur as she removed her mouth, trailing down off her boobies and leaking onto the floor.

"P-please, help YOURself..." she moaned, patting her huge, watermelon sized breast, "It feels so good..."

"Alright!" Spike said, leaping onto Sweetie Belle's mammary and beginning to suck on her teat. Soon enough, between his legs, Spike's long, hard, throbbing dragon sock was being rubbed up against her soft fur and flesh, his hips swaying around as he massaged her boob with his claws. "It's so delicious!" he said, suckling like there was no tomorrow.

"Oh! Oh! Oooooh..." Sweetie Belle continued moaning, her milk covered tail wagging behind her, "Oh please don't stop! Oh! Ooooh-Ow! Hey no biting!"

Rarity stood there, blankly staring at the trio on the floor, Twilight grasping her boob with both forelegs and suckling intensely on the teat in pure bliss while Spike's rubbed his claws all over her other breast. All of them were being drenched in milk, but they didn't seem to care. Rarity's face gradually contorted as she became more and more horrified, culminating in absolute terror as a stray splash of milk hit her on the forehead.

Then, Rarity passed out.

Author's Note

Okay, last time I apologized for a random delay between chapters, then this one took even longer, so I'll shut up about it. Also, I got a little adventurous with the narration, hopefully it's good.

Someone better call social services, 'cause I'm abusing those italics!