"You'll really do anything I want?" Sarah asked with no small amount of disbelief.
"Yep! Anything you want, I promised." Jennifer said happily. Sarau looked eager.
"Oh yeah, prove it. Take off your soaked panties, put on my dry ones. Then piss through them onto my shirt, while playing with your tits," Sarah commanded, blushing. She'd only met one girl who would partake in her fetish, and she left right after. She never even called.
Jennifer, unexpectedly didn't seem disgusted. She just smiled, and lowered her friend's panties. She took of her own and threw them in Sarah''s face, landing with a wet 'slap'. She slipped the dry pair on and climbed on the seat, her pussy pointed directly at her friend's tits. She hesitated to make sure Sarah really wanted this.
"Are you sure? Your shirt's going to be soaked, and you'll smell like piss." Jennifer asked, using all her willpower to resist letting go.
Sarah just laughed. "I'm already covered in your delicious cum, I don't think it'll make much of a difference. Besides, if I'm covered in piss, maybe Principle Johnson will let me off. I've heard she's got a piss fetish. Maybe I'll get some action from her too." Jennifer nodded, and let go, unable to resist anymore.
It started slow at first, just a few drops appearing on the fabric of the panties. Then there was a stream, beating down on Sarah''s flannel shirt, soaking the cloth. Sarah had stopped noticing after that and was just rubbing her sizable tits as a golden shower of piss rained down on them.
She was moaning louder than the engine, and there could be no doubt what they were doing. But other than the boys nearest staring and rubbing their hard dicks through their jeans, no one acted as though this was strange. It was as if an extremely busty, topless redhead pissing on her best friend was completely natural. It was so arousing that even if she hadn't been ordered to, Jennifer would be roughly pawing at her tits.
Finally she ran out of pee, and Sarah pulled her down onto her lap for a steamy make out session. They kissed and played with each other's bodies almost ten minutes before Sarah broke away from Jennifer and whispered in her ear.
"Piss again, I want you to pee in my lap." Jennifer was just about to respond that she was empty when she found that her bladder was full again. Shrugging it off in the sexual haze, she let her muscles relax, and she began to pee on her friends lap. Jennifer felt Sarah jeans become soaked in her own urine and moaned.
She once again emptied her bladder on her friend and plunged her hand past the waistband and into her friend's cunt, furiously punping it in and out. She was surprised to feel a jet of water shoot out at her hand. Sarah was pissing herself! They both came at the same moment, Sarah from Jennifer's hand, and Jennifer from humping her soak jeans. They both came down from their sexual high right as the bus pulled up to the school. Jennifer stood up, her legs and tits soaked in piss. Sarah looked the same, except she was wearing more clothes. They shared one last kiss before departing the bus.