Sorority

Warning: this story is a fantasy and details sexual behaviour that is, at best ill-advised. But it is pretend, so so long as you aren't a doofus, you should be ok. All sex-acts described are within ages of consent in the country it's written in (England, for the record).

I'll try to keep the parts and the action coming!

*

"Other stuff?" asked 23-year old Penny, enjoying the sensation of cuddling her almost nude step-sister, her firm, C-cup boobs squashed against Natalie's F-cup tits, whilst her hands stroked the 19-year old's recently spanked bottom. Unbeknown to the girls, their older sister, Hannah, 25, was standing observing them.

"Yeah...other stuff," Natalie almost whispered, snuggling against the dark-haired girl. "When I wet the bed last night, I did it on purpose." Hannah's ears pricked up at this -- Penny had claimed that she was the one who had pissed in the bed. "And I do that a lot -- I love to wet my knickers and the bed, especially if I could get caught. It just turns me on."

"I was shocked, at first," began Penny. "But, when you left me laying their after you peed on me, I was...I was really excited too."

Natalie smiled. "I want to, to...just, keep holding me." Penny frowned, wondering what Natalie meant, but hugged her step-sister closer, cupping and squeezing her round, spanked bottom.

Penny felt Natalie tense up. The ginger girl had her eyes closed and looked to be concentrating. As a sob escaped her, Penny felt a wetness on her pussy and realised that Natalie was again pissing on her, but she made no move to stop her, her nipples hardening in excitement as she lay in bed being pissed on by her sister for the second time in 12 hours. Natalie bit her lower lip and screwed up her forehead. The flow of hot wee stopped, and Penny was about to tell her to carry on when she felt Natalie tense up again and, suddenly, she was simultaneously aware of three things -- a bad smell, a soft, crackling sound and a bulge forming in Natalie's panties, under her hands. Natalie was shitting herself!

Hannah had to bite on her fist to stop herself from making a sound as she spied on her sisters. She'd heard Natalie's confession to enjoying wetting herself with disbelief and a thrill -- going to the toilet in her knickers was one of Hannah's secret pleasures. As she watched Natalie piss over Penny, Hannah could feel her own nipples hardening, her D-cup breasts responding to the shock of what she was seeing. And then it got better. Hannah could not believe her eyes as the back of Natalie's piss-wet briefs tented out and filled with a large, soft turd. Not only that, but instead of recoiling in horror, Penny seemed ok with this development, and kept stroking and cupping Nat's bottom, even as a second piece of poo joined the first, smearing brown fudge over Natalie's pink cheeks. Hannah slipped a hand into her jeans and began to gently stroke herself as she watched.

Natalie had been almost paralysed with tension as the first thick turd pushed out into her knickers. She figured she had enough blackmail material on Penny to keep her quiet if she was disgusted and ran screaming from the room, but she wanted her step-sister to share this with her too. When she felt Penny's fingers still tentatively cup her cheeks as her panties filled with poo, she was emboldened and relieved to relaxed a little and let a second piece of dirt out. She felt Penny press slightly against her stained panty pouch, spreading the shit over Natalie's spanked ass. Thrilled by this mute acceptance, Natalie opened her eyes and kissed Penny full on the lips. Her older step-sister returned the kiss with passion, and Natalie relaxed fully, dribbling more piss into her stained gusset to soak through against Penny's pussy, and finishing the dump she was taking in her panties.

Penny had been stunned by what was happening. The fresh flow of piss had felt so exciting as it bubbled through Nat's panties and ran over the lips of her cunt, and she'd been about to suggest licking Nat again when the poo started. At first she was too shocked to say or do anything, but by the time the second lump started to squeeze out her heart-rate had stabilised and she realised that she was so turned on that she thought she might explode. She knew this was disgusting and weird behaviour, but the heat between her legs told her that she didn't care. She ran her hands across the foul bulge in Natalie's panties, testing the firmness and gently squashing, feeling the hot, soft poo smear across Natalie's hot, soft cheeks. She returned Natalie's kiss hungrily, and was delighted to feel the bulge in her step-sister's panties grow, as Natalie squeezed out a third and final turd, this one the largest of the three. It filled the whole back of her panties and, thanks to Penny's gently kneading fingers, squashed down between her legs to touch her pussy lips. Penny was less gentle now, mashing the shit against Natalie's bottom and kneading the back of her knickers, whist grinding her pussy against her step-sister's. "You're so dirty," she whispered, between kisses. As the poo squeezed out of the elastic around Natalie's cheeks, Penny realised she was getting the slimy, brown mess on her hands too.

Hannah's hand was a frantic presence between her legs, her panties so wet with her juices that she may as well have wet herself too. She was utterly transfixed by the actions of her sisters and the filthy, lesbian sex they were engaged in. She was torn between revealing herself and seeing if they minded her joining in and staying where she was to see how it played out. However, she was more forceful than the younger girls and Natalie already looked like she'd been spanked -- Hannah quite liked the idea of dominating her sisters and forcing them to let her join in. The thought almost triggered her orgasm.

Natalie felt like she was in heaven. She'd been soundly spanked and was now in bed with her step-sister, both slippery with piss, her panties full of shit, her tongue in Penny's mouth. She was so horny that she was prepared to do almost literally anything. She could feel the sticky poo smudged all over her cheeks and smeared against the bottom of her pussy and knew that her panties were ruined. "Can you go, Pen?" she asked.

"What?"

"Do you need the toilet at all?" Penny paused, then nodded. Natalie broke their embrace and rolled on her back, loving the shifting weight of the mass in her knickers and caring not a bit about the mess they were making in Hannah's spare room. She shoved one hand down the front of her panties and started to finger herself, her palm pressing her clit, whilst her other hand started to roughly twist her nipples and maul her huge, soft tits. "Do it on me!" she implored.

Penny bit her lip, but swiftly made up her mind, and straddled Natalie. She too began to play with the ginger girl's tits, accidentally leaving streaks of shit on them from where she'd been cupping Natalie's dirty bottom. The sight of this drove both girls wild (and Hannah too, not that they knew) and Penny pressed her cunt against Nat's face, grinding as Nat immediately started to lick her. As soon as she felt her sister's tongue in her pussy, Penny let go. A hot stream of piss bubbled out of her and blasted straight into Natalie's face, filling her welcome mouth, splashing over her pretty features and streaming down her shit-smeared body. She tried to swallow Penny's piss whilst still licking and sucking at her pussy and fingering herself. Both girls were moaning and grunting, slaves to their passion and the whole dirty carry on was too much. They came almost simultaneously, moaning and sobbing, Penny with her pissy cunt against Natalie's mouth, Natalie with shit on her boobs and four fingers deep in her pussy.

They were joined in their orgasm by a wide-eyed Hannah, who bit painfully on her fist as she came, not wanting to betray her presence. She'd decided that she didn't want to let on that she'd seen the girls as a plan formed -- a plan that allowed Hannah to indulge in her sickest fantasies, just as her sisters had.

To be continued...