Unsurprisingly, they were all thinking about dick

Marie cleared her throat. "I was kind of wondering what it would be like to have a penis. Like, you clearly enjoyed it a lot, so I wanted to at least give it a try. But with kind of a feminine aesthetic, if that's possible. I mean, not to say that I don't think you're feminine now, especially with your body and makeup! I mean—"

"Marie, calm down."

Marie wasn't sure whether Jackie knew the right tone to take, or if it had simply been an irresistible order. "Okay."

"It's true that I wasn't going for any particular aesthetic, beyond size. And there's so much written about the concept of a feminine penis; it's no trouble at all."

Marie gasped as she found herself wearing a frilly swimsuit. And again as she felt a sensation of pressure and need at her crotch. As her flesh swelled, the bottom of her swimsuit formed into a sleeve around it. A dainty mushroom-shaped head peeked through, followed by a smooth shaft, the same light tan as the rest of her body, with subtle veins barely protruding from the surface. Below, two comparatively small testicles nestled in a smooth sac with fine hair. At the same time, all of her existing features were enhanced and softened.

"Okay, now that she's broken the ice, I also want to try having a cock, but I've got a different aesthetic in mind. I've always admired the athleticism of horses, so I want to try being a centaur!"

Lisa started as she found herself wearing a sports bra with no bottom, then fell to her knees at the sensation of much more growing than Marie had dealt with. Her torso lengthened and darkened, before two new arms emerged from below her ribs, first growing brawny, but then thinning, as the nails broadened and flattened, before all but the center nails shrank away, the remaining two nails growing into hooves. Above her new forelimbs, her chest muscles gained definition. Below, she stumbled to her hooves and feet, as the changes worked their way down. New ribs grew in, housing lungs that drew their first breath from... it's not important. Dark brown fur sprouted from a rapidly growing torso, and as her hips and legs reshaped themselves, one last change began, small in relation to the others, but oh so pleasurable. The skin in front of Lisa's now-leathery pussy scrunched up and then bulged outward, growing into a pair of testicles even larger than what Jackie's normal-sized body sported, and a sheath that quickly disgorged several feet of erect horsecock.

"Thanks for being honest with yourselves! The forms you picked out for yourselves are perfect, because you picked them, and if you change your minds later, your new forms will be perfect, too. As for myself, I was considering what I'd like for the beach, and I came up with something a little different to try." She instantly changed into what looked like a pretty conventional bikini, although the bottom was, of course, more like a scrap of fabric wrapped around the very tip of her erect penis. But then the cups began to bulge outward, pushed away from her breasts by the growing shafts of her nipples. As they grew longer and longer, two mushroom-shaped heads developed, until Jackie's bikini was stretched into uselessness by three mammoth erect dicks. "All right, let's hit the beach!"