Back to school

Shelby woke up the next morning feeling funny. Her butt was full of urine, so it was natural to feel weird, though. She reached her hand between her crack and felt her GirlPlug which held the urine inside her. Not a drop had leaked, thank goodness. She didn't want that nastiness ruining her sheets, and perhaps more importantly, she wanted to keep it inside her so she could drink it this day to get her daily quota of piss to keep her body beautiful.

The other reason she felt weird was what else had happened to her the previous evening. Her brother and his loser friend had sex with her, and not very consensual sex. She was naked in Greg's room and let the boys pee into her butt, so she knew she couldn't really claim to have been violated out of the blue. She knew what she was risking getting boys horny like that. She hadn't had a lot of choice in the sex, and now she'd had **** with her brother finally, and might even be pregnant for all she knew. She didn't really mind the sex, it had actually felt good, and probably half the girls in school had sex with their brothers at least once if they were honest about it. Something about being used like that because the boys were too horny for her actually made her happy, on a perverse level.

But it was a school day and she couldn't think about such things. She stumbled to her feet and took a shower in the bathroom she shared with Greg. For a once he actually gave her space and didn't come in to ogle her as she cleaned herself or shaved her legs. She was very aware of the urine sloshing around in her rectum. It was such a weird thing, and gross perhaps, but it was a very practical way to keep a supply of warm, healthy urine ready to drink when she needed it. She'd abandon the whole silly affair except when she stepped on the scale that morning, she'd weighed 100 pounds, and some of that was urine. Despite being so light she hadn't lost anything from her big breasts, which were her signature feature. Her waist was so small and her chest was so big, there was no way she could maintain this ideal physique without urine. She wasn't even hungry despite having just **** down a grapefruit for breakfast as she dressed.

She was running late so she got her school things together in a hurry and went straight to the car where Greg was already in the passenger seat. He didn't bitch about her making them late or even complain about her playing her favorite female singer on the car stereo. Wow, Shelby thought, he actually feels guilty about forcing me to have sex. She didn't know her brother had a conscience.

Shelby drove them to school without conversation, needing the drive to calm down and get ready for her day. She supposed what had happened the night before was just one of those things, it didn't have to mean anything. She might even want it to happen again, especially with just Greg. That was fucked up, but so was everything about life these days. She just had to accept the parts she liked and go forward.

She parked in the school lot and Greg started to get out of the car wordlessly.

"Where are you going?" she said, "You need to pee in my mouth first."

Greg looked to her, shocked that his sister would want him to pee in her mouth after he more-or-less **** her the night before.

"You're not saving it for that Eleanor Landry are you?" Shelby asked with her old spunk.

"N-no!" Greg said. Well, Eleanor would be pissed that she wasn't going to literally be pissed, but he'd deal with that when he got to it. His relationship with his sister was more important.

He got on his knees facing her on the seat and she leaned over, casually taking his cock into her mouth after he unzipped and offered it to her. By now he was used to using girl's mouths as urinals, but it still felt great. He started to piss on her tongue and filled his sister's mouth with his hot liquid. She tapped his butt and he made himself stop, with great difficulty, and she swallowed his urine down. He felt her lips and tongue move over his shaft as she **** down the hot piss, and that felt icnredible for him.

The parking lot was busy with activity as students ran in now, since the tardy bell was near. If anyone noticed Greg peeing in his sister's mouth, they didn't care. Most girls in school these days were piss-drinkers, it seemed, it was glorious. She tapped his butt and he resumed peeing, groaning as he unloaded his bladder into Shelby's willing mouth. He didn't know how girls could make themselves drink piss at all, let alone so much of it, but he was happy they did.

Finally his bladder was empty and he shook his dick inside her mouth, giving her the last few droplets of urine she craved. To his surprise, she only tightened her lips and started to suck him off. This was her reaction to getting quasi-****? Giving him a consensual blowjob? Greg didn't think he'd ever understand women.

But he was horny as hell and found it impossible to resist. In fact, this new dimension of his sister turned him on so much he had to cum immediately. He grabbed her hair and **** his eight-inch cock all the way down her throat. Shelby's eyes went wide and she gagged. Greg didn't care. His sister's tight, urine-lubricated throat felt perfect. He pressed his balls against her chin and held his cock deep inside her and started to cum. He felt like he was shooting his sperm straight into his sister's belly as his dick twitched and sperm poured out. Shelby had **** but to swallow, if this even counted as swallowing since he was cumming right down her pipe.

Greg pulled out with a loud slurping noise and Shelby grabbed a bunch of tissues to clean up quickly.

"Aren't we going to be late?" he asked.

"You are," she said, "I am going to the nurse's though. That will excuse me for first period."

"Oh," Greg said. He thought about asking why she was going to the nurse's, but realized it must be to get a pill to try to not get pregnant. He had no interest in talking to her about that, he felt so guilty still.

"See you after school? You can give Eleanor the rest of your pee today," Shelby said as she touched up her makeup in the mirror.

"Y-yeah," Greg said, "Love you, Shelby."

"Love you, Greg," she said back. She didn't even sound mad. Greg really did love his sister.