Mike was a 10 year old boy. He had ordered SWAPP online and had gotten it just recently. He waited so his parents were out of the house and his 18 year old big brother was sleeping with his girlfriend. Mike had always wanted to find out what it was like as a girl and he was tired of being a guy anyway. He had the perfect subject and that was his brother's girlfriend. He had already stolen her panties when his brother took him to her house. Now all Mike had to do was get her to drink the SWAPP with him. It was easy. His brother had fallen asleep and his girlfriend was up doing homework. "Hey Lisa. I have a drink for you and for my bro," said Mike. "Oh that's great! Come in Mike!" she replied back. Mike went in and gave her the drink laced with SWAPP. "Thanks!" "Your welcome!" Mike left quickly and went to get SWAPP and drank it. He didn't feel anything at first, but soon started to feel a pain in his groin. He took off all the clothes off his 10 year old body and started to see the changes. His small dick started to grow as it went erect to almost 10 inches. He had seen his brother do this before, but it had never happened to himself. He took the chance to jerk off like his brother. He felt great pleasure in doing just that and he felt he actually might regret becoming a women. His dick stayed erect as he noticed his whole body started to grow and become feminine his came to rest at 5' 5". His skin soon turned silky smooth and he next noticed that his chest was expanding and mounds came to make his C-cup breast. His hair also grew out and turned into a ginger. The final change then occurred as his erect dick began to shrink and went into his body and the balls soon followed after. The transformation was complete. Mike, now Lisa went to look at his new bod and admired it for several minutes. He then went to bring his clothes to the real Lisa and steal her now too short for her clothes. (S)he went back to her brothers room and was just in time to see Lisa transform. She had taken her clothes off too (An exact Mirror to Mike) "Mike! What the hell is going on?!" She had no time to react though as the changes started in opposite order of Mike. The balls came out form the clit. They looked even hairier the her brother, but her attention was focused on the dick coming out. It crawled out of her vagina and went erect at at massive 1' 6''. "EEEEEEEEEEEEEK!!!!" she yelled out, but it did't wake Mike now Lisa's brother up as the voice became lower. Her hair jutted in and turned black and her boobs shrank down in to a man's chest. She shrunk into a 10 year old and her body turned into that of a boy. The dick then shrank down back into what it was supposed to be. That of a 10 year old's. Both of their transformations were now complete. "What... What happened to me?" Lisa now Mike asked. "You've been SWAPPed. Now take these clothes and behave like a good little boy, while I fuck your boyfriend.