Jen pulled herself from the exhausted horse. She began to make her way back to another corner of the barn when suddenly she felt a tingling sensation coming from her groin. Looking down in confusion, she noticed it had become rather swollen in size. Poking at it quizzically she found that it had increased too in sensitivity. Then out of no where she felt a massive pressure forming from inside. She immediately dropped to the ground as she writhed in pain. Jen likened the feeling to what giving birth must feel like. She grabbed each side of her vagina and pulled it apart, hoping to get out whatever was inside her. She ould feel it sliding out, inside of her, something long and tubular. Looking down she saw the mushroom head of a horse's penis. "Oh god!" She thought. "I'm growing a horse cock!". Jennifer screamed out loud and continued to push until all 8 inches flopped out of her and onto the ground. Jennifer lay there on the ground covered in sweat, recovering her breath, until finally she decided to face reality.
She looked between her legs to confirm the obvious. Her penis was still there. "Ugh..." She groaned. Curious, she began to poke and prod it, it sprang to life instantly adding another inch to it's mammoth length. Stroking it she began to notice how good it felt, even letting her mind wander to using it to fuck someone, "Oh how good that would feel!" She thought.
Then suddenly...