Applejack finished storing the last barrel of apples for the day. The day had been harder than usual because her big brother had been bedridden all day, but some help from her friends (and a "teamwork exercise" from the School of Friendship) had taken care of his part of the work.
"Ho boy, directing that many ponies at once was more trouble than bucking all the apples myself would have been!" Applejack sighed as she headed to the kitchen to get herself a refreshing glass of cider. To her delight, Big Mac was already downstairs and digging through the fridge, meaning he must have been feeling better by now.
"Howdy big brother!" Applejack quipped, causing Big Mac to almost jump out of his skin as he spun around to face her.
"Eeyup!" he said awkwardly. His expression was so embarrassed that even a blind pony would have sensed it.
Applejack simply laughed it off. He was such a hard-working pony that staying at home during applebucking season must have been embarrassing.
"Don't worry Big Mac. You’re a hard worker, and everypony knows you wouldn’t fake a sickness to shrink from a job.” she said reassuringly. “Now move over, I’m feeling thirstier than a sheep in midsummer!”
“Eheh, eyup!” Big Mac nodded, realizing he was still standing in front of the fridge. He started slowly shuffling to the side with wobbly steps, facing Applejack all the way. Now this was getting mighty suspicious, and his desperate expression betrayed that he darn well knew it himself.
“Big Mac? Are you hiding something?” Applejack asked with a raised eyebrow, freezing Big Mac in place.
“N-nope!” he said with a gulp. Applejack tried to peek behind him to see what he was hiding, but he had backed himself into a corner and was vehement about blocking her line of sight. What he hadn’t counted on was Applejack suddenly dropping prone and getting a clear view from between his legs.
“Sweet Celestia what happened to your balls?!” Applejack cried out. Her brother wasn’t called Big Mac for nothing, but by the sight in front of her he should have been called Big Watermelon instead. Mac quickly tried to block her view by closing his front legs, which did nothing to hide the two hoofball-sized testicles swaying between his rear legs. Big Mac let out a resigned sigh.
“I may have stepped into something in the Everfree Forest.” he admitted. Hanging his head, he turned around to give his sister a better look. The secret was out so there was no point trying to hide it any longer.
“Poison Joke?” Applejack asked, tracing her hoof over one of the huge ovals.
“Eyup.” he answered, twitching lightly from the mares touch. He tried to focus his thoughts on work and apples to keep something else from growing between his legs from all the attention his balls were getting. She sat down to heft them with both of her hooves, giving him a brief relief from their weight. She kept talking as she examined his orbs, but all his concentration went to trying to keep his looming erection under control. Unfortunately, it was a losing battle.
“...but waiting this long before seeing Zecora was just plain reckless!” Applejack finished, patting one of the balls just hard enough to send them swinging.
“Gah!" Big Mac winced at the shock traveling through his nut, his shaft now half stiff from the stimulation. Poison Joke hadn’t affected it like his balls, but that didn’t make its normal size any less formidable. The precum dripping from it, on the other hoof, was an order of magnitude more than what was natural.
“Do you smell that?” Applejack asked, leaning past Mac’s giant balls to see his dong flopping out and dripping. “Oh no, not on the kitchen floor!”
Big Mac inhaled to say something, but was quickly interrupted by Applejack ramming her head right into his swollen balls. His words were replaced by a girlish squeal as Applejack hastily pushed him into the bathroom, his testicles dented by her forehead lifting his entire rear end into the air as she moved him onto the tile floor. As soon as he was past the bathroom doorway she grabbed a towel, heading back to wipe the snail trail he'd unwittingly left behind. Big Mac let out a soft whine as he stood still, his testicles throbbing where Applejack’s head had squished them against his pelvis.
Applejack trotted back into the bathroom and tossed the cum-soaked towel into the sink. “Okay big guy, deal with it quickly so we can get you to Zecora before sundown.” she sighed, tossing the dirty towel to soak in the sink.
Big Mac looked away and blushed. “It uh... doesn’t work that way.”
“What? Can’t you just... you know...” Applejack looked back at Big Mac with a quizzical look, doing a back and forth motion with her hoof.
“Nope.” Big Mac said and plopped down on his haunces, wincing as his balls hit the floor harder than expected. “For some reason ah can’t feel my own hooves on it.” Mac sighed, patting his engorged member back and forth while Applejack looked at it curiously. ”Ah just watched Flutt- somepony bucking apples today and it didn‘t go down for two hours.”
The gears were starting to turn in Applejack‘s head as a new idea formed in her mind. “Hang on a second... Has this been going on since your applesack swelled up?” she asked, walking over to her sitting brother.
“Eyup.” Big Mac nodded.
Applejack sat in front of him with a knowing smile. “I think these balls are just a side-effect, not the joke itself.” she said, patting one of his balls for emphasis. Mac inhaled sharply as her hoof bounced on his tender nut, waves of pain traveling through it with each little impact. He thought about reminding her about how sensitive a stallion’s balls were, but that lecture always appeared to fall on deaf ears so it was better to just bear with her and get this over with.
“Can you feel this?” Applejack asked, reaching forward to brush his cock with her hoof. Big Mac’s relieved expression answered everything before he did. “Eyup.”
Applejack scooched forward to wrap her hoof properly around his shaft and started slowly pumping it up and down. “The Poison Joke just made you super pent-up. That’s why these two are so swollen!” she said, using her free hoof to ruffle his other ball like the back of a dog. Her hoof grinding against his testicle made Mac squeal and flail helplessly, elicting an amused chuckle from his sister. There was no way she wasn’t enjoying his discomfort!
She enjoyed making him squeal like this for a while before finally moving both of her hooves onto his cock. In any other circumstances Big Mac would have already curled up in foetal position to nurse his aching balls, but Applejack was his only hope for relief now so he’d just have to deal with the pain while she was feeling helpful. He concentrated on the feeling of his sisters hooves rubbing his shaft, and as she got the last giggles out of her system she got into a proper rhythm with long up-down strokes.
Applejack watched her brother lean back and let out a pleased groan, his cock wobbling in front of her face in rhythm with her hooves. She kept telling herself she was doing this only to relieve her brother, but it was getting harder and harder to deny that feeling the thick, meaty shaft between her hooves wasn’t turning her on. She bit her lip as she watched precum flow from its tip, looking so appealing she was having a hard time keeping from licking it.
“What the hay, it’s not like he’s going to complain!” she thought to herself, going all-in and plopping the head of his cock into her mouth. Big Mac gasped, the feeling of Applejack’s warm mouth taking the experience to an entirely new level. He moaned and reached a hoof to rub her head, overwhelmed by pleasure as his sister started bopping up and down on him. “F-faster...” he moaned, tilting his head back as he rapidly approached his limit.
Applejack was going as fast and as deep as she could from her current position. She reached her right hoof down to shift herself a little, unwittingly putting her weight on one of Big Mac’s aching testicles. Big Mac sucked air through his teeth as his sensitive nut got squashed, trying not to interrupt Applejack and make her stop when he was this close to orgasm. Instead he pressed on, grabbing Applejack’s head with both hooves and rapidly driving it down five more times, cumming in her mouth just as she put her other hoof down on his free testicle for more support. Big Mac cried out in pleasure and pain as his cock exploded in her mouth, causing Applejack to push down hard on both his balls to wrest her head free from the literal bucketload of cum shooting into her mouth. His orgasm was absolutely mind-shattering, almost enough to cover the crushing agony of his gigantic testicles getting stomped on by his sisters hooves.
Applejack finished coughing out the semen she had accidentally inhaled, using a hoof to wipe off some of the goop covering her face. Big Mac was still squealing in foetal position, holding his balls in his lap with huge squirts of cum still spurting out from his twitching member. The whole room looked like somepony had emptied a large fire-extinguisher inside it. If this didn’t take care of her brothers nuts, she didn’t know what would!
“Whoo-ey!” she exclaimed, standing up on the sticky yet slippery floor. “Now let’s take another look at those apples.”
Big Mac finally finished cumming and rolled onto his back, his legs spread and his softening cock flopping onto his relieved body. Applejack leaned down to inspect his balls, and could have sworn he had passed out if he hadn't twitched the moment her forehoof touched his sack. “Boys... are they ever not touchy about their nuts?” she thought with a smile.
Big Mac’s head was floating between the afterglow of his orgasm and the throbbing of his nuts. He was too tired to move a muscle while Applejack examined his abused ballsack. At least he was, until she finished her inspection.
“They haven’t changed a bit? Horsefeathers!” she yelled, giving his nuts a frustrated kick from her forehoof. Big Mac yelped and curled up again, his previous relaxation gone in an instant. “Let’s get cleaned up, looks like we’ll have to find Zecora after all.”
While his sister took a shower to wash the cum off herself, Big Machintosh recovered enough to stand up on his wobbly legs. He slowly lifted his balls of the floor, feeling their every movement as they rose from the floor to hang in his sack again. The ache would have been enough to disable a lesser stallion, but by the time Applejack finished cleaning up he was already ready for his turn in the shower. He scrubbed himself clean, his heavy testicles swaying with his movements. Scrubbing them was an ordeal in itself, as after the bruising Applejack gave them even the slightest touch was enough to hurt.
When Big Mac got out of the shower, Applejack was already waiting impatiently for him. “Ready to go big brother?” she asked.
“Eyup” Big Mac answered, even forcing a little smile. Walking all the way to Zecora’s hut wasn’t pleasant with sore nuts, let alone ones that hung halway to the ground and kept bumping against his hind legs.
The trek to Zecora’s hut was uneventful. Applejack walked behind Big Mac to watch his wide-legged gait, chuckling at the way his balls bounced around. The manliest bits of a stallion being the most vulnerable had always amused her, but this massive pair bouncing in front of her was something else entirely. She just wanted to touch them, feel them on her hooves, to squeeze them tighter and tighter as her brother squealed like a filly... She caught herself drooling and shook her head from side to side to clear such thoughts from it.
Finally the ponies arrived at Zecora’s hut and Big Mac knocked on her door. It didn’t take long for Zecora to answer, surprised to see the two Apple siblings. “What a surprise, it is Big Mac! What brings you here with Applejack?”
Big Mac hadn’t thought of how embarrassing this situation would be, but with a blush heavy enough to show through his red fur he slowly turned around.
“Oh my goodness, what a pair! No wonder you came to my lair!” Zecora gasped.
“Eyup.” Big Mac replied bluntly.
“Yeah, apparently he walked into Poison Joke yesterday and spent the whole day in bed, too embarrassed to get out of his room. Can you help him?” Applejack clarified.
Big Mac stood still as Zecora took a close look at his balls, poking them with a forehoof just hard enough to make him wince at each new jolt of pain.
Zecora finally stopped poking his nuts and lifted her head from them. “These may or may not be a trick of the flower. Step inside and I’ll look them over.”
Big Mac followed Zecora into her hut, with Applejack following close behind him. Zecora sat down on a pillow and gestured him to approach. “Step over here and turn your back, I need to see your giant sack.”
“Eyup.” Big Mac responded, backing his rear end to Zecora. To his surprise, he first felt Zecora press her muzzle against his nutsack, and then give one of his balls a firm, painful slap with her hoof.
“Gah!” he cried out, legs trembling from the sudden pain.
“Try to hold still, my poor red stallion. I need to find out what is going on.” Zecora adviced.
Big Mac gritted his teeth and stood still as Zecora looked over his balls again before giving him another hard smack into his other nut. He grunted and fought to stay standing despite the pain and nausea of the impact, only to be followed by another hard blow straight to the underside of his hanging balls.
With shaky legs, Big mac let out a sigh of relief as he felt Zecora moving away from him, only to get surprised by both his balls getting smashed hard as the zebra straight-up bucked him. “AAAGH!” he yelled, the sudden explosion of pain overwhelming him instantly and dropping him like a bag of apples. He curled up in agony, his bruised balls throbbing in more painfully than he could have imagined. He was having trouble breathing, let alone asking what the hay she did that for.
He didn’t need to ask though, as Zecora cleared her throat and proclaimed her diagnosis. “Is he affected by Poison Joke? It turns out the answer is ’nope’.”
Applejack let out a worried gasp. Big Mac was completely preoccupied with nursing his hurt testicles, only wishing for the nauseating pain to end somehow.
“It’s another plant, like a puch to the gut, a nightmare of stallions called Bustnut. It’s fruit causes stallion’s nutsack to grow, but makes it a target for kick and a blow. Mares find their size extremely appealing, but the cause of their lust will leave the male screaming.”
Applejack was listening intently. “So this Bustnut plant...”
”...It gives stallion victims a gigantic sack, and the mares a compulsion to give it a whack.” Zecora confirmed. She then turned to gently pet Big Mac‘s head and continued. “But worry not, for there is a cure, although it is rather hard to endure. It cannot be cured by drinking or eating, your balls will shrink down only through beating.”
Big Mac could only look incredulously as Applejack asked what he was already thinking. “Beating his balls?
Zecora nodded. “His nuts will need be beaten down, to ever get them back to the size of their own.”
Applejack threw up her hooves and let out an incredulous laugh. “Did you hear that big brother? Sounds like you’ve been already getting the right treatment and didn’t even know it!”
Big Mac couldn’t believe is ears. His poor balls were already in more pain than he’d wish to his worst enemy, and they needed to be abused even more? Zecora noticed his despair and cheered him up with the first good news of the day.
“I’ll make you a mug of my pain-relief brew. It should take a good while before pain starts anew.”
They weren’t great news, but right now he was happy to make the pain stop for any amount of time.
Big Mac carefully drank out the last few drops of Zecora’s brew. It wasn’t tasty, but it was really helping numb the pain so he made sure not to leave a single drop of it behind. The two mares were chatting happily, laughing and sharing stories of all the times they’d busted some unfortunate stallion’s balls one way or another. Either his Bustnut affliction was affecting them, or his aching balls just made him pay more attention to things that could potentially threaten them.
As the two ponies walked out the door, Zecora gave Big Mac’s balls one more slap for the road, just hard enough to make him yelp and bring his tail down to protect them.
“There’s one more thing I must confess, about beating your balls to an aching mess. They never needed my painful procedure, but I too am not immune to Bustnut’s lure!” she laughed heartily. Big Mac stared daggers at her, but at least the brew she had given was working well enough that that last hit had hurt no more than a punch to the shoulder.
The trek back to the Sweet Apple Acres was as uneventful as the trip to Zecora had been, but far, far worse. Applejack was again walking behind Big Mac, but this time she was intentionally walking too close to him and “accidentally” kicking him in the nuts once in a while. At first it had been painful but mostly annoying, but the effects of the pain-numbing brew were waning and the kicks starting to hurt properly again, in addition to the lingering pain of the abuse his balls had taken at Zecora's hooves. Towards the end of the trek the effect of the potion had ran out almost completely, leaving Big Mac hobbling toward home as fast as his sore balls would allow while his sister tried to giddily poke them with her hooves every chance she got. He was relieved to finally reach the farm, because even if the worst was yet to come, at least he didn’t have to worry about reaching home before the pain incapacitated him.
“I’ll be in mah bedroom.” Big Mac stated as soon as he got inside. He didn’t know what Applejack had in mind, but he needed a while to rest his balls.
“Okay big brother! See you in a minute!” Applejack chirped back, way too excited for her brothers liking. She hummed happily with her tail held high like she had been waiting for this the whole day. Which she probably had, at least since Zecora gave her the a-ok for busting his balls.
Big Mac got to his room and carefully climbed onto his bed, slowly lowering his aching balls onto the mattress between his legs. He hadn’t realized how heart-pounding the trip home had been before now, as his relaxing pulse made the throbbing in his balls more distinct, each beat of his heart thumping his balls like an explosion. At least they appeared to be visibly smaller than they’d been in the morning so all this ”treatment” hadn’t been for nothing.
“Are you ready Big Mac?” Applejack asked leaning against his doorframe.
“Nope.” he answered, laying down on his back nevertheless. It was time to take his medicine.
“Well buckle up because here I come!” Applejack said, giddily trotting to the end of her brother’s bed. “Oh, I’m more excited than a squirrel in a barrel of nuts!”
Big Mac grimaced. Applejack climbed onto the bed as his brother backed up on it, partly to give her more room, and partly out of fear over how excited she appeared about this. He suddenly found himself hoping he’d have saved Zecora’s brew until getting home after all.
“Uh, Applejack? Are you feeling okay?” he asked hesitantly. “Yep! Never better!” Applejack quipped back, softly lifting his balls onto her hooves and pressing her muzzle against them. She was being much more gentle than he’d expected, and her soft touch combined with her warm breath was starting to have an effect on him.
She took a long deep whiff of his balls, completely enraptured by their scent. Big Mac wondered if he should remind her what she was supposed to be doing, but if there was a silver lining to this mess there was no way he’d spoil it. Applejack moved her hooves around his balls, letting them slip from her hooves onto the bed and sliding her hooves on top of them. With a satisfied hum she pressed down on the two orbs, elicting pained squeals from her brother as she increased her pressure. The mattress beneath them yielded softly to a point, but Applejack’s hooves pressing against his sensitive testicles was sheer agony.
Applejack smiled, slowly releasing her pressure and moving one hoof to pull Big Mac’s half erect cock against her cheek. ”I sure am enjoying this more than you big brother, but don’t you worry, I ain’t leaving you hanging either.” Big Mac, still catching his breath after her last crunch, watched on as Applejack gave his shaft a long, passionate lick while caressing its other side with her hoof. He was still wobbly from the pain, but the mares touch was still enough to coax him to attention. He thought she was going to start fellating him again, but instead she slammed her free hoof right in the middle of his balls. It happened in a blink of an eye, but he felt every tiny detail of his balls slipping and compressing underneath her hoof.
”AAUGH! Just... get it over with, will ya!?” Big Mac yelled, desperately wriggling his back legs in the air around Applejack’s body in an attempt to ease the pain in his agonized balls.
”I will, I will. Don’t you worry about it.” Applejack responded. ”But it’s not everyday a stallion asks to get his balls beaten so I’m enjoying it while it lasts!”
Big Mac opened his mouth to retort to that, but was cut off as another hoof struck his painfully swollen nuts. She really had him by the balls in every sense of the word. Another blow struck his balls, prompting him to yank the pillow from under his head and bite down on it as Applejack started punching his nuts with alternating hooves.
Big Mac screamed into his pillow as his sister mercilessly pounded his balls, his whole lower body flooded with unimaginable pain radiating from his testicles. After an eternity her beating started to slow down, the last few blows coming down sparse but hard, with one last punch clearly being the hardest his sister could muster. Big mac opened his tearful eyes and let the pillow out of his mouth, looking down at his slowly deflating shaft and her sister getting down to inspect her hoofwork.
”Would you look at that. They’re starting to look more normal again!” she said, rolling them painfully from one hoof to another. ”Normal for you that is, they always were on the larger side.”
”Is... it over?” Big Mac asked with a quiet, wavering voice. He couldn’t tell what the dimensions of his groin were anymore as all he could sense between his legs was a blur of inconceivable agony. He did feel it when Applejack let his testicles drop from her hooves though, gasping at the pain of their movement as she stood up on all fours and moved up to stand above him.
”Better make sure.” Applejack whispered into his ear before kicking him in the balls three more times with her rear hoof. Big Mac screamed, each kick a few seconds apart and hard enough to squash both his balls flat. ”There!” she finally said, satisfied with the bucking of a lifetime she’d just finished.
Big Mac whimpered softly as he tried to curl up into a ball, but Applejack looming above stopped him. Confused, he looked up into her eyes, seeing her smile warmly before planting a soft kiss on his nose. ”You made it through, big brother. Now it’s time for your reward.”
Applejack sat down on his belly, his cock trapped between him and Applejack’s pussy. She started rubbing herself back and forth against his member, the soft hairs of her tail brushing gently against his bruised balls. He finally let out a relieved moan, weakly moving his hooves to caress her flank as his cock started stiffening again.
”Sis... should we-” Big Mac started, but Applejack shushed him gently. ”Hush now brother. Don’t spoil the moment.”
With Big Mac back at full mast, Applejack stood up again and backed her pussy against the tip of his member. She got up on her rear legs, using her front hooves to guide him against her opening as she lowered herself on him. Big Mac breathed deeply as his stallionhood slowly sank deeper into her warmth. She was dripping wet, no doubt having enjoyed herself the entire time she busted his balls.
Taking it slowly, she eventually took him inside her all the way, her warm plot landing into Big Mac’s lap. Even without direct contact he could feel her weight above his balls, but despite all they had just gone through, he wasn’t going to go to sleep with blue balls.
Applejack breathed deeply, getting used to the huge cock inside her. She started to slowly move up and down along its length, her brothers hooves resting gently on her hips. Big Mac groaned in pleasure, waiting for Applejack to come down one more time before starting to gently pump his member into her.
Applejack quickly got into the pace, bringing her plot down to meet her brothers thrusts. He grunted as the movement made his sore testicles jolt around, but he needed release for the pent-up energy of his formerly gigantic balls. Gritting his teeth, he grabbed her by the flank and started ramming into her as fast as he could, racing against pain towards his orgasm.
”Hoo-o-boy!” Applejack gasped as his brother took control, pistoning his cock in and out of her like a machine. It was her turn to be out of breath, trying to hold on as her brother kept ramming his cock inside her like never before. She soon screamed wildly as her orgasm hit her, brought over the edge by the sheer intensity of her brother’s thrusting. Her body clenching wildly around his length, it didn’t take long for him to cum too, and with an animalistic roar he thrust inside her one last time. He could feel the force of his load taking off all the way in his contracting balls, his massive load traveling up his cock and shooting inside his sisters vagina. Several more followed, the pressurized liquid rapidly filling her and splashing out between her lips and his shaft. With one last squirt, his body fell limp with Applejack still in his lap, his erection starting to soften inside her.
Applejack took a moment to catch her breath, her mind hazy from the intensity of the experience. ”W-wow, Big Mac! That was incredible!” she exclaimed, wiping the sweat from her forehead. It hadn’t been wild just for her though, as her brother had literally blacked out underneat her. Applejack stood up, the remaining lenght of his brother plopping out of her as it slowly shrunk back down into its sheath. Careful not to wake him up, Applejack got off the bed and planted a good night kiss on his forehead.
”Goodnight, big brother. I promise tomorrow will be much better.”
Big Mac woke up to the crow of the rooster, immediately reminded of last evening’s activities by the booming ache between his legs. He carefully reached under his blanket to feel his balls, wincing as he gingerly felt them with the tip of his hoof. They were painfully swollen, but fortunately no more than was expected from this kind of bruising. There was also a molten bag of ice in the bed between his legs, although he couldn’t remember where he’d got it from.
”You awake big brother?” Applejack’s voice came from the hallway.
”Eyup.” replied Big Mac, placing his hooves back on top of his blanket.
Applejack opened the door with her forehoof, carrying a loaded breakfast tray in her mouth. On the tray she had an apple pie, a glass of cider, and a freshly cooled bag of ice. Big Mac watched as Applejack set the tray down on his nightstand before turning to face him.
”How are you feeling? Still sore down there?” she asked.
”Eyup.” Big Mac replied.
Applejack blushed lightly and drew circles with her forehoof as she spoke. ”I uh, brought you some ice, if it helps. I may not know how the guy parts work, but colts always seem to want ice on their balls when they’ve been a hit.”
”Eyup.” Big Mac agreed. His sister taking care of him like this was very sweet of her, in contrast to the beating she’d given him yesterday.
”So, if there’s anything I can do for them- I mean you, just ask, ok?” she finished, preparing to leave to let his brother rest in peace.
”Applejack?” he said, stopping her before she could go. ”Could we just... cuddle for a while?"
Applejack smiled as her blushing brother shuffled to the side of his bed, making room for her to join him.
”Aww, I love you big brother!” she said and slipped under the blanket next to him. Big Mac wrapped his hooves around his sister, embracing her snugly as she shuffled into position next to him. Laying there with his loving sister, his tender balls resting gently against her rear leg, this was the coziest comfort he could dream of.
The End
Author's Note
This is my first finished story for the April Sibling Incest Contest. I originally tried to write about Luna and Celestia, but after 600 words I had to admit that I have no idea how to write about two female characters. After starting a new story with some balls to bust I wrote the first 2300 words on the first day alone. 
I hope you enjoyed it!
