As I was staring and contemplating what species the appendage should be, I began to notice something. I always had a little internal habit of comparing people to certain animals, normally based on some physical detail. She had a nice ass, due to her constant running and training. It was pert, large (but not to large), firm, and nicely muscled, much like an ass should be. So, while I was debating what to put on her, I remembered what I always compared her to. A donkey, whom is in name an ass.
So, I wished for her to live up to her name. "I wish that Jennifer had a donkey tail."
A shiver seemed to run down her spine and I saw the lowest part, just above her tight butt, begin to bulge out. The tail extended out excruciatingly slow, vertebrae by vertebrae. All the while her face slowly contorted into a grimace of pain and she seemed to slow her run and lean forward. By the time it reached it's full length at about two feet she had come to a stop and look almost like she was going to scream. Rapidly, short gray fur grew over it, changing into long and thick black hairs at the very tip making a nice tuft. It shivered once then began a slow wave to the side. All this probably happened in under a minute real time, but seemed to be at least ten to me.
I stood watching, and though this was a good view, I really wanted to see her reaction. So I made two wishes. First, that no one would notice me or run into me. Second, I wished for time to speed back up to normal. As she was already in the process of stopping during the slow down, She came to a complete stop after time returned to normal. She doubled over and put her hands on her knees, panting and grimacing. Slowly, she turned her head and opened her eyes, catching the tail just as it flicked into sight. She screamed again and resumed running. I had a hell of a time keeping up with her, and had to slow down time a few more times just to catch up, but eventually she rounded a corner and collapsed onto the ground. Between gasps I thought I could hear something that sounded like... sobs.
As she was on the ground, I took the opportunity to look around. I hadn't realized how far we had come. She wasn't the star runner for nothing. We had made it all the way out of town, past the suburbs, and into he rural area. I wasn't exactly sure where, but I think we were in a barn on some farm. A few of the pens where open and empty, but most were closed. I turned back and watched her as she stood up and slowly turn and grab her new tail tentatively in her hand.
Looking now, after all that running, she now looked a bit... incomplete. She needed a bit more. But, what...