"Jen, remember not to masturbate so much. The doctors said that if you do, you'll grow another vagina" Jen didn't know how to respond to that. A second pussy? She hadn't really masturbated that much anyway, so there's no need to worry.
She then suddenly remembered how she masturbated through all of the previous class, and immediately started to feel a tingle around her crotch, and looked down to see. She realized this tingle must be caused by that second pussy the teacher was talking about! The tingle grew more and more intense, until she came from the sensation. She looked down, and now she had two pussies, both constantly pissing. Jen started thinking if she would keep growing more if she kept on masturbating.
So, she gave it a shot, since she was still horny from the piss, and put both her hands into each their pussy, and started to masturbate. This felt twice as good as it did when she masturbated with only one pussy! Well, she did now have twice the amount of pussies she used to have too. After cumming multiple times, she started to feel the tingle again. Her theory was correct, and of course again, the tingle grew so intense, she came again. She looked down. She had three pussies now. She decided to stop at that, even though she felt incredibly horny because of the piss, she still resisted masturbating.
The gym class is soon over and people are getting up from the piss filled pool.