Erika smiled deviously. "Since you didn't seem to think twice about screwing me," she answered, "I've got the perfect new form for you. For your transformation, I want you to turn into a nice big living cock."
Jennifer gasped in horror. "No! Erika! Anything but that! I know you're angry at me, but... please, not that!"
"Yes, that. You're going to be a living penis. No legs, just a penis. You'll be four inches long when you're flaccid, but when you get hard, you'll swell up to a nice big nine inches. Like, you won't have eyes or ears or an actual mouth, but you'll still be able to see and hear and speak from your little hole. You won't be able to move on your own, and since you won't have a stomach, you won't need to eat or drink. You won't have to pee either, but you will be able to cum when you get off-- in fact, you'll be super-horny all the time, and you won't be able to satisfy the feeling unless you cum. Your cum won't be able to make me or anyone else pregnant, but it will immediately cause anyone who comes into contact with it to have a really powerful orgasm-- so powerful, in fact, that anyone else aside from me will be willing to do anything I say just to have some more of your cum. Oh, yes, Jen-- I'm going to love using you as my own little personal sex toy."
With tears beginning to well up in her eyes, Jennifer suddenly felt compelled to deliver Erika's dare. "Transform or d-dare."
"Transform," said Erika, not wasting a moment.
"You will return to your normal body," Jennifer sighed, the tears rolling down her vulva. "No one will notice anything different about you. The only thing that will be different is that you will have a permanent ability to use Transform or Dare. No matter how much you use it, you will have an infinite number of turns. If anyone tries to use it on you, you will be immune to the effects, and the person who tried to use it on you will feel them instead."
Suddenly Erika felt herself changing-- growing upward. The fleshy dome above her waist began to expand upward, forming a torso and taking her eyes upward with it. Soon enough, she once again had two arms, a head, and a pair of lovely breasts. Finally, her hair-- both on her head and above her pussy-- returned to normal. When she looked down at herself, she found she was back to her regular body, naked though it was.
"I'm back to normal!" she shouted in joy. After looking herself over a few more moments, she turned to find that Jen's changes were just beginning. Erika found herself entranced by the sight-- she could not turn away. Jennifer began to shrink; within seconds she was a quarter the height of Erika, rather than a half. Soon Jennifer's clitoris began to balloon outward, taking on an oblong and distinctly phallic shape. "Nooo!" screamed Jennifer. "Erika! Stop thiiiii--" But Jen's voice was cut off as her pussy lips fused together and began to inflate as well. Soon the little creature Jen had become was completely laughable in appearance-- a huge bulging penis and balls which were freakishly disproportionate to her rapidly dwindling legs. Before long, her oversized genitalia was way too heavy for her to remain upright, and she toppled back onto what was now her scrotum, which caused her shaft to droop down. At last, her eyes swelled shut, disappearing completely into her flesh. Jennifer Smith, one of the most popular girls in school, had now been reduced to nothing more than a living, disembodied penis.
Erika stooped down to get a better look. She called softly. "Jen?" There was no response, so Erika once more asked, "Jen?" As she did so this time, she lightly poked the creature with her finger. The reaction was immediate. Jen's shaft throbbed to life, perking up.
"Erika?" asked the Jen-penis in a somewhat more androgynous voice. "Erika... have pussy?"
"Yes, Jen," answered Erika, picking up her friend and holding her up near her exposed slit. "Erika have pussy."
Jen shivered in delight. "Jen penis. Jen horny. Want Erika pussy."
Erika lifted the Jen-penis just in front of her face to get an eye-to-glans view. "Shh," she said mischievously, holding up an extended index finger to Jen's hole to shush her. There was already a small bead of anticipatory precum. "Like, don't you worry, my little pet. If you're a good little cock, we'll get to the main act very soon. But first... Erika wants to play around with her new toy a little."