You glance around the store. You see all sorts of costumes. Werewolves, superheroes, erotic costumes all strung up around the room. But soon you spot your favorite, a horse man costume covered in brown fur and a black mane on top. This will be perfect and original, no one will have the same costume as you. The only downside was the costumes ridiculously large cock and balls, but you figure you can either cut them off or just wear clothes over them. You take the costume into the fitting room and strip off your clothes. You unzip the zipper of the costume and slide both feet into the legs. You hesitate for a moment but decide to slide your junk into the costumes. You now slide your arms inside, lift up the mask over your head like a hood and zip up the back. You just stare at yourself in the mirror. You look good! You've always been kind of chubby but the costume makes you look incredibly muscular and well toned giving your body a very sleek shape. It's suprisingly confortable too, you wiggle your toes and stretch to test your full range of movement. It's pratically like it's your own skin and the mask doesn't limit your vison at all, you love this costume. You decide to buy it. You reach to your back to search for the zipper to remove the costume, but you cant find it. You keep trying but no luck. You get an idea though you reach into your discarded pants pocket and pull out your cell phone and snap photo's of your back to help yourself find it. You look at your phone and are shocked to find that there is no visible zipper. You look in the mirror and open your mouth to find that the snout opens up too revealing two rows of large horse teeth. The costume has combined with you transforming you into an anthro horse. You start laughing, you feel great. You feel your brown furry body, touching your horse face, arms, torso and ass. Last but not least you grip your massive cock. When it was a costume piece it was embaressing but now that it's now your real penis your pretty damn proud of it and your ready to start using it. You feel it harden up in your hands, realizing that there will be no way to put your pants back on with it being erect, you grab your shirt and start jacking off into it. It feels so damn good you can't help but let out a loud moan of pleasure as you cum into your T-shirt. Time to leave the fitting room. You slide your shoes on your, thankfully not hooven feet, put your pants on, tightening the belt tighter than usaul. But you elect not to put on your cum filled shirt, instead letting your brown fur covered six-pac remain exposed as you exit the changing room.