Obligatory warning: contains scenes of genital torture and dreams of castration. Dont read if you arent here for that.
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It was a warm day, perfect for a bit of outdoors sport. Max's favorite kind of day. As a young cheetah he had great pride in his speed and athletic skill, thoughts of scoring another winning goal running through his head as he headed for school. Nobody could keep up with him and nobody could catch him once he was fired up and he wasn't about to let that change. Today was going to be a good day, he was sure of it. 
All that stood between him and another good game was a short stint in health class.
To his and everyone else's surprise though, this health class was one of the easy ones - just watching a video. As Max sits back comfortably the room dims, the title of the video popping in. Preventing Genital Injury Part 1. 
There was a slight worried murmur among the students but it was soon drowned out by music and narration. The video starts off with a boy skateboarding, doing a few tricks in what feels like a genuine if low-effort skating video. It's all pretty normal stuff until he tries to grind a rail, slips, and lands crotch first on it. The image freezes as most guys in class gasp in sympathy as the narrator beings talking. 
'A familiar sight to many. A carefree good time cut short by an accident. While being mindful of what you're doing can help prevent accidents, what's more important is preventing injury from them.' The still image highlights the boy's helmet, his gloves, elbow pads, knee pads, and crotch. 'Wearing a helmet, pads, gloves and cup can mean the difference between an embarrassing fall, and a trip to the hospital'. 
The video continues as the boy falls off the rail, hits his elbow off the pavement and winces in pain for a moment before standing back up and skating away. It then cuts to another boy who isnt wearing any protective gear, opting for a tank top, ripped jeans and a beanie for style over function. He tries the same rail grind and similarly slips and falls, his fall accompanied by a wet crunching noise as his groin impacts the rail. As the image freezes, there is an audible gasp among every guy watching. Rather than showing more, the video transitions to an animated diagram showing a pair of testicles to the amusement of some of the girls present. The narrator returns to explain 
'It is easy to imagine a bruise, bump or broken bone from taking a bad fall which is why many remember to guard against those. But it is equally important to prevent less visible injuries, such as damage to the testicles'. 
There is a stunned silence among the class as the animated diagram shows the pair of balls hitting the metal rail in slow motion, denting out of shape as they are crushed between the unyielding rail and the rest of the boy's body until they rupture like a pair of ripe fruit making that same wet crunch they all heard before.
Like all the guys watching, Max felt his testicles shrivel at the sight. His hands felt weak and he could swear he felt a lingering sympathy pain in his gut. It had never really crossed his mind before, but now that the point had been driven home so clearly, he instinctively moved his shaking hands to cover his crotch, still unable to look away from the video. 
As the narrator continued talking about damage from bruising to swelling, more scenes played out similarly - a boy getting into an accident, followed by an animated diagram showing the damage to their nuts from getting hit down there with a hard baseball pitch, their friend stepping on a rake and sending the handle flying up between their legs, sitting down and dropping a schoolbag on the ballbag, and getting kicked during a football match.
The last one hit Max the hardest as he had seen many accidental kicks on the field before, just never one hitting there. It was because of this that the narrator's words were realy etched into his brain: '...repeated or very hard damage can lead to permanent destruction of the testicles, castration. This is why it's so important to wear a cup.' 
The video ends on a screen saying to continue to Part 2, but that would have to wait for next time as the bell rings, sending everyone outside. As he walked out of class, one word kept echoing through Max's head relentlessly. 
Castration.
Heading outside, he caught snippets of conversation, other students talking about what they had seen. One guy remarked how glad he was he brought his cup today. A girl wondered if balls really made that sound. Max felt vulnerable. He had never thought much about his boyhood, only considering it a source of power for his athletics. Even today he had left his cup home because he thought it was just uncomfortable and slowed him down. His balls felt like they were aching and his limbs felt like jelly as he flashed back to some of the scenes and diagrams, doing his best to push it all out of his head until he heard an all too familiar wet squish. 
Looking down, someone had dropped a few cherries from their lunch and he had stepped on one. His mouth felt dry as he lifted his foot, seeing a pair of cherries with one having popped into a red pulp under his step, splattered on the groud. He remembered the video saying a testicle was no harder to pop than a firm fruit, and he hadnt even noticed the cherry as he stepped on it. With a trembling hand, Max picked up the other cherry, pinching it between his fingers with a quivering lip as he felt the flesh of the fruit crush in his grip until it burst into his hand without much effort at all. The boy gasped, dropping the cherry and stepping away from it, his other hand creeping down to cradle his balls. 
He hurried away, wanting to be anywhere but here, thinking anything but this. On his way to the football field he saw a few girl on their way as well. He didn't hear what they were saying but clearly saw the one in the middle of the group, a strong-legged bunny, taking a walnut from a paper back she was carrying, and cracking the shell before eating it. He didn't need to hear what they said after all, as he was convinced they were talking about pulling a guys nuts out of his sack and breaking them like she was demonstrating. There was no way she could just be having a snack. It had to be a warning.
In the locker room Max's mood mellowed out a bit. The familiar setting helped put him at ease and flush away the thoughts that had been haunting him. This was going to be a good day, and a good game. His focus only broke for a moment as he saw the boy next to him put his cup on, making Max reflect on his bare jewels and how they were hanging there, unprotected. He didnt lose focus for long through as he pulled up his shorts and headed out to the field, confident that no harm could come to him. After all, nobody could catch him. 
This assumption was proven correct almost as soon as the match began. Displaying his usual speed and agility, Max was able to easily stay ahead of everyone else, scoring a few goals and controling the ball with ease. It all went perfectly until near the end of class he tried to go for a pass, only to notice a familiar face running to intercept him. It was the bunny from earlier, her strong legs carrying her at impressive speed as she looked determined to stop Max's winning streak. A flash to her breaking the walnut open shook Max, making him hesitate for a split second. 
This critical mistake threw him off and his foot landed on top of the ball rather than behind it, his kick turning into an awkward stumble as he tried to stop himself from falling over, bracing his legs into a wide stance. This in turn made the ball roll off to the side, and as the bunny was already swinging her foot to go for it, it was too late to prevent disaster. Her foot slammed into his wide open groin at full force, the impact smashing his unprotected testicles up into his pelvis with terrible force. For a moment time stood still for Max. He saw the girl's foot in his crotch, he saw the shock on her face, and in the distance he could hear the ref blowing their whistle. 
Then the pain caught up to him.
A wave of agony radiated up from his jewels as his legs went limp, reaching his gut by the the time he fell over and curled up, hands desperately shielding the battered orbs. His vision blurred and his ears were filled with the rush of adrenaline as he gasped for breath. The ref and coach had rushed over, turning him on his back and pulling his hands away to check if he was ok. His head was too full of pain to register anything they were saying, but the coach placed an ice pack on his balls, urging him to get up and go home. He limped to the benches tightly pressing the ice against his crotch fighting back the urge to puke or cry. While he managed that much, he could not escape the horrifying thought of what damage that kick had done down there.
During his entire shaky walk home he didnt dare to even touch, let alone look at his aching balls. Out of sight, out of mind was the best he could do to not freak out despite every step feeling like another kick impacting his groin. It wasn't until he got home and was sure he was alone that he finally dared to strip off his gym shorts and take a look in the mirror. His testicles looked like they had swolen to twice their usual size, every small prod and press he dared to try sending fresh spikes of pain through his body. He tried to pull his shorts back on but gave up, wincing in pain and deciding to instead try and sleep if off. His distended sack swung around as he walked to his room and climed into bed, even the pressure of the soft covers enough to make him shift uncomfortably. A few minutes later, he finally found a position he could live with and drifted off.
Max found himself back on the football field, still without his shorts. He looked around and saw every other player was a girl, all of them also bottomless. They were all staring at him with menacing smiles, eyeing up his aching balls as they approached. He looked down as well, and saw his balls had swolen further, his sack now nearly resembling a football. To his horror he quickly put two and two together. He wasn't a player here. He was the ball.
The coach blew their whistle and both teams of girls ran at him. Max tried to instinctively run, but every step he tried to take was slowed down by the pain in his nuts until one of the girls caught up to him, slamming her foot into the back of his ballsack and sending him stumbling down the field. Before he could recover and stand up, another girl rushed in and kicked his balls from the side, her toes sinking into them as her kick sent him towards the goal. He stopped shortly before the goalposts, panting on all fours as his balls throbbed, hanging hot and low between his legs. He didnt have long to catch his breath however, as another girl's foot kicked up into the bottom of his sack, flipping him over by the balls, landing on his back in the goal where he curled up as the whistle sounded again.
The girls grabbed him from the goal, dragging him back to the center of the field. Too weak to stand from the pain, the cheetah found himself held up by this arms by the girls, his legs forced wide leaving the battered sack between them hanging in plain view.
Through the haze of pain he recognised the girl walking up to her - she had been there before, on the football field! She was the one who had kicked him, starting all this. Now, it looked like she was going to finish the job. The nude bunny reached down between his limp legs and wrapped her fingers around his swolen testicles, feeling them roughly enough to make his guts turn.
"Look at how big they are now. Looks like they might pop any second!"
He tries to protest, but his words were drowned out by the other girls around them eagerly starting to chant "Pop! Pop! Pop!"
As the chanting grew faster and more aggressive, the bunny let go of his aching boyhood and took a step back, winding up a big kick with a wicked grin on her face. Before the cheetah could so much as plead for mercy, the foot slammed into his bruised boyhood, painfully crushing it against his pelvis. As the wave of increasing pain shot through his body the girl readied another kick, followed by another, and another, each harder than the last. His tortured orbs were pushed to their limit, swelling and denting out of shape until the fifth hard kick finally pushed them too far.
As his testicles reached breaking point the pain radiating from his groin suddenly doubled, jolting him awake from the haze of agony he had been fighting through. His body went limp and his mind could only focus on one thing - the broken mush that a moment ago had been his balls.
As the girls around him started cheering, the bunny stopped and reached down again, pressing her fingers around the sack to check her handiwork. Each small pinch and rub felt worse than any kick before as she made sure he was well and truly no longer a boy. Convinced the nuts were beyond saving she gave him one final grin, squeezing the ruined sack in her hand.
"Enjoy being castrated, loser."
The girls holding him let go and he fell to his knees, then on the ground clutching what little was left of his jewels, closing his eyes and whimpering as the girls around him laughed, his head spinning and the world going dark.
As he opened his eyes, he saw only his dark bedroom ceiling. Panicking, he reached down to feel his package, and was relieved beyond belief to find two firm balls still there, along with a large cum stain all over his sheets. For a long while he just stayed there, wondering what on earth had gotten into him to give him such weird wet dreams.
The next day Max was back in class, the horrors of the night before still vivid in his head. Through the day he caught several glimpses of the bunny girl from before. He wasn't sure if it was coincidence, or if he just paid more attention to her now, but he couldn't help but feel she was looking at him a lot. At the end of the day she finally approached him, taking him behind the school with a slight blush.
"Hey uh... I just wanted to say... sorry about... you know. Yesterday."
Her sincere and slightly embarrassed words took Max by surprise and he tried to play it cool, giving her a thumbs up and a grin
"It's fiiiine... no harm done."
She persisted, crossing her arms
"No it's not fine, I want to make it up to you somehow. Maybe I could... let you kick me down there too?"
The suggestion wasn't what Max was expecting, but it sounded fair. With a nod he set up for a kick and she looked around to make sure they were alone before spreading her legs for him and giving him a nod. The cheetah's foot flew up into her crotch with quite some force, lifting her on tip toes for a second with a wet splat audible from her groin. Max looked a bit spooked, worried he had broken something as she gritted her teeth, hands crading her pussy as her legs wobbled. She drew a few sharp and shaky breaths, then returned his earlier thumbs up, one hand still between her legs.
"N-now we're even. I'm Jenny."
"I'm uh... Max. No hard feelings, right?"
The two parted ways with a smile, Jenny walking with the same slight wobble Max had endured the day before. This was the beginning of a strange but fruitful friendship.