James sat on the side of his bed, idly toying with his junk through his tight underwear. He had chosen orange this morning out of his collection of various types and colors, but the orange one was his favorite. His fingers caressed and traced the round rise of his small package, causing him to moan compulsively, his body shuddering at the contact.

As he continued to stroke, James felt his loins throb beneath their orange cloth confines, his cock beginning to awaken. James found himself tipping over the edge, the horse wanted out, and he couldn’t fight it. Wouldn’t fight it. Not this time.

His muscles pulsed under his skin as tendrils of silken brown fur sprouted from his blushing hot skin. The thrumming of his heart sped up as he felt himself grow larger inside, his bones and muscles thickening, preparing for their inevitable outward expansion. With a series of sharp and dull cracks James’s body grew larger and larger, putting on feet of height as his muscles bulged along with his growing cock.

James felt himself letting go, the horse taking over his thoughts, filling him with desire. An insatiable desire for sex that nothing but shoving his growing cock deep inside something tight and wet, over and over, for hours and hours, could abate. He whinnied as his face crunched and cracked longer and thicker, his jaws distending into a long horse muzzle, his nostrils growing and flaring. His body now that of a body-builder, thick ribs of muscle cascading down his sides as his broad pecs jiggled in his all-consuming heat.

As his body reshaped so did his family jewels. His balls swelled larger and larger with every beat of his ever-increasing heart rate. His virile orbs pushing out of the tightening leg holes of his underwear as their turned deep obsidian black. The orbs grew and grew, the skin around them tightening uncomfortably as they filled with equine seed. James’s balls swelling to the size of oranges and beyond, pushing his legs apart with their sensitive girth as the underwear clung ever-more desperately to the keeping cleft between to the horse orbs pulsing between his legs. He nickered loudly as the balls dropped lower and lower, his crotch getting heavier by the second as his tongue lolled uncontrollably out of the side of his mouth.

His cock pulsed thicker and thicker as it formed a medial ring. Its length growing well beyond the thickness of a coke-can as the skin of his penis tightened over the lengthening and throbbing organ, turning black and pink. His meager five-inch length soon giving way to a throbbing rod almost a foot-and-a-half long. His pointed human head flattening and flaring into its distinct equine shape as he began leaking his slick lubricating juices from his gaping urethra. His underwear couldn’t hold him, the fabric tearing, barely holding as it forced his cock into a painful arch. James’s changing and thickening hand gripped the wall, grasping for support as his body completed the change. His thickly-fingered hand tearing long gashes into the drywall as his huge flat teeth ground in his mouth. The pleasure mixing with the pain was overwhelming and divine, his voice deep as he bellowed and neighed in ecstasy, his crotch throbbing madly.