"What!?" You yell. "I don't want ot be a colt! I just wanted to buy the diaper! I didn't know it was magical, I really didn't! Please, help me! Change me back!"
"Oh really? Jenny says slowly, her face changing, dropping the smile and suddenly becoming serious. She puts down the towel and picked up a pare of shears.
"What are you doing?" You say with apprehension. She walks over ot you and quickly slicks the shears under your shirt, slicing it in half. The shirt falls to the dirt, leaving you completely naked with your hands tied to the bar in front of you.
"You don't want to be a colt?" she says, now sounding more serious than ever. She runs her hand along your back again, down from your shoulders to the base of your spine and down your long, brown tail. You shiver again, your erect horse cock feeling very aroused. You let out another horse like snort. "But you like this feeling so much," she says, now seductively. "If you don't want to be a colt, why not be a stallion?"
You look at her in desperation, but an evil grin has appeared on the horse-girls face. She reaches down below and grabs your large cock. You yelp in surprise and pleasure as she begins to pump it furiously.
"Wha.." You gasp as waves of pleasure stem from between your legs. Jenny laughs and you can feel a pressure building up in your bowels again. She continues to pump, and you can feel yourself coming to a climax. Then She stops abruptly, leaving your desperate cock hanging free, throbbing with need.
She reaches up under you and brings her face up to yours, then kisses you firmly on the lips. As she pulls back, you can see animalistic need in her eyes.
"I really need a big, strong stallion inside of me, you want that, right?"
Your mind tries to say no, but your new erect member has other plans. All you can do is pant and nod.
She turns over under you, and you can hear her zipper as her pants come off. Then you feel a tickling sensation on your cock. and underside. Jenny's tail rubs against you as her body pushes up under yours. The tip of your cock touches something wet and slimy, and you realize that Jenny's Vagina isn't where a normal woman's is. It is much lower between here legs, like a horses. She can probably only be taken from behind with it. Her tail brushing your underside is making your mind wild, and you realize that you are about to horse-fuck a horse girl.
"Take me, please!" She pants desperately.
Your legs buck unconsciously, and the tip of your penis slides around her waiting hole. After several tries, it finds it's mark, and you can feel your large cock squeeze into her. She moans in ecstasy as you slide in, the pleasure almost overwhelming for your still human brain.
Then, too late, you realize that the pressure in your bowels has been growing to an uncontrollable amount. You gasp as you let loose a load of horse shit that falls down you and Jenny's legs, giving off the overpowering smell of horse manure.
"Yes!" Jenny screams "Yes, that's it, you are a stallion! Shit like a stallion!"
Your thighs buck Jenny as the pressure in your bowels builds again.
Then, with a crushing orgasm, you let loose another load of shit as your cock explodes into Jenny. You both let out loud screams that sound more like whinnies that echo across the courtyard.