Jimmy Sanders was standing by himself as usual when the announcement came over the speakers. He looked around, trying to spot one of the teachers, but only saw the other kids. Overweight and more interested in TV than anything else, he didn't have a lot of friends, and none on the field trip.
"This is boring." He muttered mostly to himself. "Screw this, I'm gonna look around." Maybe there was a snack machine, or better yet, a visitor center with air conditioning. He was hot and sweaty already.
Just around the corner from where the kids were gathered, he caught a flash of black and white. Zebras - he'd seen them before, of course, but something about them sparked his interest and he walked over to the edge of the habitat. Pretty. A couple of the animals scented him and walked over to investigate, though they couldn't get close due to the tall fence.
Jimmy pressed against the barrier, fascinated by the closest animal. She was beautiful! Funny, he'd never noticed how graceful and alluring Zebras were. She was incredible. Jimmy shifted uncomfortably as his pants caught over his crotch. He reached down absently to shift his normally small package, and then jerked his head down when his hand found a massive swelling.
"What the fuck!" His pants were tented out incredibly far, and the pressure on his groin was getting painful enough that he yanked his belt open. The heavy dark shaft that flopped out made him, and some of the people around him, gasp. His dick had never been that big! Shit! It was almost as big as...
Jimmy looked back at the Zebras and realized that the other was a male who had dropped his dick as well, and the two bore a striking resemblance. In fact, his penis and balls kept changing until they were identical to the stallion's!
Now he really felt hot, but it was all through his body. The female turned away from him, and her thick black cunt squeezed and then relaxed. Though he had never been round animals like this before, Jimmy suddenly knew she wanted him - and HE WANTED HER!
The need to fuck filled his mind, and he threw himself against the fence. People around him shouted and backed away, but he only had eyes and ears for the female who kept winking her sex at him. Lucky for him, the fence had been designed to keep casual bystanders out and the Zebras in. He was able to climb over, dropping down in the animal side and staggering toward the still-waiting female. The stallion wheezed and bucked, but did not interfere.
Jimmy moved behind the female, his cock now fully swollen into that of a stallion, and guided the flared, black cap in. With a powerful thrust, he fell over her back and started humping. The intense sexual need was getting more powerful with each thrust, and he found that mating was also getting easier. He shifted forward, pushing harder with stronger legs.
He was dimly aware of screams and shouts from spectators, but it was hard to focus on anything other than the female. Her scent filled his nostrils, which flared as he curled his upper lip. Vision was blurring, and something seemed to be blocking more and more of his forward vision.
Jimmy shifted forward again, covering the female's entire back now, His arms were stiff and fingers and toes were numb, yet the sensations were oddly familiar. He also noticed that his peripheral vision was expanding - moving further back.
It was only when he finally caught sight of the black and white stripes sweeping back from his shoulders that Jimmy finally realized what was happening, but by then it was far too late. Already mostly animal, he was unable to stop mating until he shuddered in release with a guttural sound that matched the female's. Dazed, he slid off her back and stood there as she rubbed against him in welcome.
He was a Zebra!