After school Tiffany rode the bus back with Sarah. They ordered some pizza and hung out. Tiffany asked where Sarahs parents were. Sarah told her the truth, about how she keeps getting younger, and it comes from wishes. Tiffany didn't believe her, so she offered to use a wish on Tiffany. The girl sat there comtemplating saying, "Well if it is true I want to be able to fuck you like a man". So Sarah granted her the wish. Tiffany sat there for a second before realizing she could grow an 8 inch penis. Then on top of that reassign her sex to be male. Even a little older like an 18 year old, but able to move between it.
"This is amazing" she said. Sarah smiled as she felt herself get smaller. She was now 12 at 4' 3" with a larger jump still, getting into growth spurt territory. Tiffany noticed and asked what was wrong. Sarah reminded her that every wish reduced her age by a year. Before anything could be said Sarah mounted Tiff the now large man and undid their pants.
She manuevered the tip to her pussy, but the issue stood that it was still to small. She wanted to try anyways and inserted just the tip. It squeezed in, but she felt it starting to tear at her. She was left sitting atop not knowing what to do. She was to small for one of her favorite things. That's when it hit her. What if she didn't have to worry about it. She made a wish that she would not be damaged by having sex with things to large for her. The glow started and she pushed harder down the shaft, filling her up until it hit her cervix. At the end there were 3 inches of penis still outside. She knew it was painful, but why not give it a shot? She pushed the penis into her womb as Tiff started coming.
Sarah was now 11 years old at 4' 1"