Author's Note
This is my story for the Kinktober 3rd writing prompt, the fetish of the day being Aquaphilia.
As always, the original prompt is in the cursive, with my writing continuing the story in regular text. Enjoy, and leave a comment if you like! 
Nuts in Hot Water
--Sonata mewled in pleasure. Living in the human world was taxing but there were silver linings to every cloud, such as the wonderful human invention pleasuring her at this moment. While humans had their faults, they had quite a few moments of genius that surprised her. Rubbing herself harder she bit her hand to muffle the loud, lewd moans she couldn't help but release. Felling the pressure on her snatch increase spurned her fingers to move faster. A few moment later the jet of the Jacuzzi made her climax. In her post orgasm daze she mused what other interesting things humans had made.--
Flash Sentry walked in flanked between Aria and Adagio. He was completely enraptured by the two naked girls flirting with him, but as soon as Adagio saw Sonata she almost lost her cool.
”Sonata! What are you doing!” she hissed, lowering her voice like it was somehow supposed to keep Flash from hearing it.
Sonata spun around, revealing a long, blue shaft with a flat tip protruding between her legs. ”Look! I have a dick!” she smiled, waving her phallus from side to side.
Adagio’s eyes bulged with rage as she gestured Sonata to cut it out and put the phallic object away. Luckily for them, Aria had managed to completely distract Flash by letting him fondle her voluptuous breasts.
”Just kidding, it’s a pool noodle.” Sonata said as she released the foam tube from her thighs and tossed it aside. ”Oh, right, sexy time.” she remembered, sitting seductively on the edge of the pool with a come-hither expression.
Flash was in the seventh heaven. Sure, these girls had turned the whole school against each other, but since they had lost their magical gems there was nothing they could do to. At least that’s how he justified this to himself, since he really didn’t want to miss out on a naked hot tub with just him and three sexy girls.
Adagio gently turned his head to face her, smiling seductively and gesturing to the pool. ”What do you say, handsome? Ready to get hot and wet?”
”Ready as ever!” he said enthusiastically. His cock had been throbbing since they’d undressed together, and he couldn’t wait for things to get wild. He and the girls descended into the water, Flash on one side of the tub between Aria and Adagio, with Sonata sitting between his legs directly opposite to him. Sonata caressed his legs as the two other girls pressed their naked bodies against his, practically sandwiching him between their big, firm boobs.
”Now then...” Adagio giggled. ”You’re Sunset’s ex-boyfriend, aren’t you?” she asked as she brushed her hand along his chest.
”Yes?” he answered. There was something ominous about how Adagio had asked that.
Aria curled her arms against his right arm, hugging it against her naked body. ”And you’re still friends, aren’t you?”
”Well, yes... sorta.” he said hesitantly. They didn’t actually talk to each other, but since she’d helped the Rainbooms defeat the sirens he at least considered her redeemed. Suddenly he realized why this discussion was filling him with such dread.
Adagio subtly curled her arms around his left arm as she whispered in his ear. ”Then what better way to send a message. Hit it, Sonata!”
He could feel the water rushing between his legs a split second before Sonata’s heel slammed into his balls. She smiled at him as she leaned her back against the end of the hot tub, her outstretched leg pinning his pelvis against the opposite wall with her foot firmly planted on his manhood.
”AARGH!” Flash yelled in pain as he tried to curl up to protect his balls, but it was too late. Aria and Adagio were squeezing his arms against their chests, with his hands firmly trapped between their thighs. His panicked eyes traveled back and forth along Sonata’s body, from her breasts floating gently in the water to her slender leg flattening his balls. As he gasped and squirmed in pain the three girls broke into evil laughter.
”How’d you like that, pony chaser?” Aria teased. Before he could even think of answering, Sonata drew her foot back, only to slam her other one right into his aching groin.
”AUUGH! My balls!” he screamed in pain, causing all the girls to erupt into laughter again.
”You like it in your balls?” Sonata asked teasingly, rapidly pumping her foot on his groin under the water. The sensation of his nuts getting jostlet by water between the stomps only added to the nauseating effect.
”No, stop!” he begged, his strength all but sapped by the foot grinding his balls.
Adagio chuckled softly. ”Give the poor boy a break, Sonata. Can’t let you have all the fun, can we?” Sonata retracted her foot from his groin, letting Flash's agonizingly throbbing nuts recover their shape. His relief was short lived before Adagio’s fingers curled around his balls, squeezing his already throbbing nuts tightly.
”I think he’s enjoying this.” Aria said as she stroked his cock, pretending not to notice his screams of pain. ”That must mean we’re being too gentle!” she cooed into his ear.
Suddenly, there was a metallic clack as a lock turned on the door. The girls went quiet and wide-eyed as the door of the room started to slowly creak open. Thinking quickly, Adagio leaped onto Flash’s lap and pulled his head down between her breasts just as a cleaning lady peered into the room.
Flash barely had time to fill his lungs before Adagio pushed his head underwater and into her bosom. With her legs spread around him his cock was now pressing right against her pussy, the pleasant turn of events momentarily distracting him from his ball pain.
”Is everything okay? I heard screaming.” the cleaning lady asked.
”Yes! We were just...” Adagio struggled for ideas, holding a forced smile as he felt Flash’s cock grind against her lower lips.
”Singing!” Sonata piped out.
The cleaning lady calmed down immediately and rolled her eyes. ”Urgh, you girls are terrible without your jewels!” she groaned as she backed away and closed the door behind her.
With the threat over, Aria and Sonata let out a sigh of relief, and Adagio let Flash surface his head and gasp for air.
”Did you hear that? She just mocked your jewels!” Adagio teased. ”Sonata, grab his arm.” she commanded as she remained on his lap. Before Flash had a chance to try anything Sonata was already at his side, wrapping her naked body around his arm. ”But it seems you might be good for something...” Adagio said as she lifted herself, reaching between her legs to guide his cock to her entrance.
Flash didn’t dare to say anything for the fear of her changing her mind, relieved when it seemed they would be finally leaving his poor balls alone. Only the presence of three hot girls, constantly squirming against him and pressing their voluptuous breasts against his skin had kept him hard through the pain of having his balls squashed repeatedly. He gasped in pleasure as Adagio slowly pressed him deeper, lightly wiggling her hips back and forth and moaning as she slowly worked her way down. As her hips touched down on his, she once again looked him in the eyes, breathing heavily.
”Mm... I can see what Sunset saw in you.” she cooed, starting to move up and down on him. Flash watched as her wet, bouncing breasts splashed against the surface of the water, the waves around them intensifying as she started picking up speed.
Feeling a bit left out, Aria reached between his legs and squeezed his balls, causing all the girls to snicker as his expression turned pained again. Encouraged by her friend, Sonata reached between his legs as well, Aria moving her hand to play with his right testicle while Sonata grabbed his left one.
”Girls... can’t we just- AUGH!” his suggestion was cut short as both girls squeezed his balls, the slight difference in timing and pressure feeling like they were going to twist his sack apart. Adagio kept on riding him, completely unaffected by his pain.
”Just stay hard, fuckboy.” she said gleefully. ”We know how to use you.”
He could only wail in pain as his genitals were completely at the siren’s mercy. Aria held tightly onto his right nut, slipping it back and forth between her fingers, while Sonata kept sharply squeezing at his other one and dragging her fingertips against his aching testicle. Finally, after minutes of excruciating torment his cock twitched, shooting his load inside Adagio as she slammed down on him one last time, moaning loudly as her pussy clamped down around him.
Adagio let out a satisfied sigh, leaning against Flash as his cock started to soften inside her. The other two girls hadn’t let go of his balls, but seeming unsure about what their leader was up to had toned down their kneading to almost pleasant caresses.
After a minute, Adagio straightened up and slowly let his cock slip out of her. ”Not bad.” she commended. ”But don’t think we’re doing this for your pleasure.” she reminded, sitting down opposite to him. Flash could only look in terror as she carefully aimed her leg and kicked out, smashing his freshly spent balls under her heel. Aria figured quickly what she was doing and grabbed his softening cock, holding it up and out of the way as Adagio started kicking both her feet, trampling his aching balls with a torrent of merciless kicks. Flash screamed for his life, his pain defying all definition as Adagio pedaled her heels against his thoroughly tenderized manhood. She bit her lip, enjoying every second of his squishy testicles deforming against the soles of her feet. She barely had to touch her pussy and she came again, orgasming from the sheer joy of hurting a guy's balls.
By the time she came with one extra long stomp, he had been reduced to a whimpering wreck. His balls had swollen like grapefruits and they were aching like every pain receptor in his body had relocated there.
Finally, Aria and Sonata let go of his hands and he could move them to cradle his testicles. The smug girls stood around him, arms crossed under their breasts and their pussies boldly at his eye level. ”Girls, I think he got the message.” Adagio stated smugly.
Aria leaned down, her breasts swinging gently as she spoke. ”We'll bust the balls of any guy Sunset Shimmer even thinks about dating!”
”And fuck them too!” Sonata added.
Adagio glared angrily at her, but decided not to mar the dramatic warning further by berating her in front of Flash. ”Come on girls, let’s go.” she said and the trio climbed out of the water, walking away chatting and laughing as Flash looked after their curvy backsides, still holding onto his swollen, agonizingly throbbing nuts. After the number they’d done to his balls, he was going to need a long while before even thinking of wearing his jeans again.
The End
