"What's that do?" Mary asked, pointing to the vial labelled "Internal/External".
"That? Well, depending on a person's gender, it will either make a woman's ovaries external, or a man's testicles internal." Danny said.
"Wow, really?"
"Sure. Want a try?" Danny asked. Mary shivered with pleasure as she look at Danny's body. He was still naked, as nudity around the barn wasn't that big of a deal. But she couldn't help but stare at Danny's limp ten inch penis.
In response Mary nodded, and took the vial from Danny. She brings it to her lips, and is pleasantly surprised by its sweet taste. She doesn't expect much to happen, but then there's a pulling feeling in her lips.
Mary gasps when she that something starts to move. Mary bends over and pulls her lips aside to look. Her clit as extended a bit, and acquired a hole at the tip. Her pee hole. And her vagina shifts backwards to make room for her descending ovaries.
Suddenly the skin in front of her vagina fuses together, and gets very heavy. Then there's a distinct pop, and two egg sized orbs fall into the skin. They pull and hang low on Mary's crotch. When she stands up, they sway and gently rub against her vagina lips. Mary shudders again. A weird tingly sensation washes over her, and she looks down in time to see a healthy bush growing over her new external ovaries.
"Wow." is all she can say. She cups her balls in her hand, loving the feeling of them. Her pussy below drips juices, and they make the wiry hair on her balls sticky. Mary licks her fingers, and almost cums from the taste alone. She feels so self conscious when she remembers she's not along.
But Danny doesn't care what Mary's doing. So long as he can join...