Jen thought about the call for most of the summer, her family went to the beach as they had planned, and Jen started to relax. She was lying, sunbathing on her towel as she tried to ignore the thought of what could happen, but then she looked up. There walking down the beach was a man, mid twenties, and built nicely, his skin tan, his muscles toned. Jen thought for a second and found herself involuntarily standing up, his head was gone and his body was walking toward her. Jen didn't know what to think as his body turned around and pressed it's back against her, his muscle and height adding to her own as she grew with his mass being added to her. She looked down, her once curvy petite body now strong and slightly masculine, and a definite bulge in her bikini bottom showed her that she had a new cock.
Her body flexed a few times to show off her new muscle and then turned to face west and took off at a sprint, Jen yelped as her fears came true, her body now ran without her guidance, who knows what would become of her now.