Honey Meadows sighed as she stretched out on her back, the unicorn taking up her favourite position on her couch. Besides, of course, lazily stretching out along her side to watch TV, with a cup of hot chocolate in her magic. Her forehooves curled up while her hinds spread out, her clit briefly winking as all sorts of perverse thoughts ran through her head, with most of them related to what toys she wanted to use this bright and warm morning. She had all sorts, suited for numerous different kinds of play. Long, flexible toys that were perfect for snaking deep up her ass, or poking far down her throat. Thick toys that could stretch out the spaces between her legs, and thin little rods that she could probe into delicate and unusual places, places most ponies wouldn't even consider! And then there was her collection of fake cocks that were the perfect size to plug up her fat, wrinkled doughnut of a tailhole.

But it wasn't her rump she was going to be touching this morning, no. She'd woken up with a craving, and after a few minutes and a choice application of a long and slender vibrator, her bladder was left nicely empty. Usually, she'd then go and pick out one of her urethra-gaping, bladder-bruising monsters, but today she went with something far simpler and innocuous.

A mesh bag of assorted marbles.

They weren't super fancy. Most of them were glass, in sizes ranging from tiny little peas to orbs with twisting patterns the size of a golfball, though the majority were the 'typical' size. She started by floating out five regular marbles, bringing them to her muzzle to plop on her tongue, rolling them around her muzzle with a hum as another five were fished from the large mesh bag with some clinks and clacks.

That second set was brought down between her legs, her clit winking out again as she stroked them up and down the thick lips of her marehood, only to line them up in a row and slip them up under her clit like a string, flowing along until they found her relaxed and quite capable urethra. Around and around they circled in her magic, until they all pressed together and slipped inside with ease. They were hardly the largest thing that had ever been in there, a little push was all that was needed to pop them all into her bladder.

Her magic released the marbles as they entered her bladder, letting them fling against her walls before rolling down to gather together at the bottom. She moaned again around the glass in her muzzle, and with a bit of a roll of her head and a flex of her tongue, she let those make their way to her throat before gulping them down, squirming at the solid lumps sliding their way towards her stomach. She had no worries about such small things, knowing quite well by now that, eventually, they'd make their way through her and out the other side. She'd found that out as a dare while she was a filly, one of the many things that helped lead to the perverted mare she was today.

With the first sets of marbles now nicely settled into her, it was time to actually start her fun. Putting the bag of remaining marbles aside, she settled back in and reached out with her magic, grasping for the five marbles that shifted about in her bladder, plucking them one at a time to start rolling around and rubbing over her internal walls. Grinding lines, massaging circles, and all sorts of other movement built up into a steady pace, more of her moans filling the air as she stimulated every inch of her stretchy bladder with the almost random touches of the marbles.

Her clit winked out again and again, juices freely flowing from her (often rightfully) ignored sex, washing down over her thick doughnut of an asshole to pool into her tail and slowly soak into the cushion of her couch. She got the removable, easy-clean ones for a reason! Her belly shifted around just a little from the motions rolling about in her bladder, extra little jolts of pleasure shooting through her whenever she came across one of the small openings to her ureters, the tubes that led up to her kidneys.

With enough force, those regular-sized marbles could fit, though the sensations were... intense, to say the least. She wasn't looking for such powerful feelings or in the mood for a masochistic stuffing, so instead of flaring her magic, she delicately fished eight of the smallest of her marbles from the bag. She barely felt them as they were brought into her bladder, pressing them to the twin openings of her ureters, bunching them up into little groups of four before a surge sent them on their way.

Her back arched, and she gasped out as her rarely-toyed tubes snuggled around the pea-sized glass balls, subtle spins and twists letting them drag and slip as they journeyed from her belly to her back, slipping into the cavity at the core of each kidney. She let them sit for the moment, slowly settling back down while getting used to the odd fullness such a penetration brought. While fucking and stuffing her urethra was exotic, it was still rather similar to more 'traditional' entrances. These deep tubes and the organs beyond, though, offered a fullness and stimulation that was unlike just getting her ass filled with cock, or feeling a flare beating the back of her bladder.

Relaxed once again, her magic took a hold of every marble within, and started to spin. The pair of four in each kidney flipped and angled about, slowly spreading to open up the space around, rubbing and tracing all the different internal details, while the marbles in both her bladder and her stomach much more quickly spread to roll all over their respective internal surfaces. Her hips humped up at the air a bit as she massaged deeply within herself, slowly but steadily building up to what was to be a good, strong orgasm.

Slowly, as her pleasure built itself up towards her climax, the unicorn squirmed more and more. Her arousal flowed freely, the cushion beneath her rump, and the part of her tail closest to that same rump quite soaked by this point. Her horn slowly got brighter too, putting more magic into the internal manipulation of her marbles. Bladder, stomach, and kidneys were rolled and massaged intensely from within, each orb pushing harder into their respective walls as they spun faster and circled about. There was even the faintest bit of motion visible through her belly from the movement within her bladder, and it was only getting clearer the harder and faster she went.

Eventually, though, she reached her peak, and what a peak it was. She didn't hold back, her clit messily punching out as her back arched, lifting her ass off of the couch as her hindlegs kicked out. She cried out loud and clear while thick, soupy marecum erupted from her, arcing through the air to heavily splatter at the far end of the couch, the soupy mess steaming as it soaked in. Sweat ran down her coat as she jerked and humped at nothing, another, thinner gush following up that first powerful squirt, this one mostly soaking her tail.

After a third that just oozed all over her fat ponut and soaked into its deep wrinkles, she thumped down heavily onto her soaked couch, panting hard while her horn went dark. In an instant, all the marbles stopped getting pushed, finishing up whatever motion they were in before all rolling to click and collect at the bottom of her belly and bladder, while her delightfully sore kidneys snugged back up on their invaders, holding them tightly.

The air was thick with the stink of her exertion and pleasure, a heavy musk of a well-pleased mare that tickled up her nose with every deep breath. She huffed it up, nostrils flaring as she settled down, a yawn quickly following as she relaxed.

She'd clean up later, yeah...

Author's Note

Well, this is quite a drop into the deep end, I suppose! Hope y'all enjoy! And don't worry, there's already more in the works, with both more 'regular' kinks, as well as even crazier stuff!