Whip-thin, covered in black fur.

James couldn't turn far enough to see his ass, but he realized two things: His hips and ass had grown considerably, muscular flesh bulging from the ripped seams of his pants, and from the corner of his eye... A whipcord-thin appendage, covered in short black fur curved from his butt, the cold from the tiled floor seeping through the coat. James mind went blank.

"What. The. Fuck?!" Lily's angry, confused voice broke him out of his stupor pretty much immediately. "Did you actually eat enough to explode your pants?"

The now be-tailed guy's head whipped around to see his step-sister glaring at him. But the lack of a horrified stare made James realize that his newly enlarged hindquarters apparently hid his tail from Lily, so she hadn't noticed. Yet. Struggling to his feet, the changed structure of his hips gave James a bit of trouble, but he found that he could control his new tail pretty well and lifted it up against his back, careful to always face Lily.

"Okay, uh, I'll... I'll get new pants," James stammered, backing away towards the door while he held up his pants with both hands. His heart beat thundered in his ears, and James felt like he was about to faint. This was too much. Too weird.

"Don't you dare ditch me," Lily scowled, turning around to angrily stack the tupperware into the dishwasher.

As soon as she had turned around completely, James whirled around himself and stumbled towards the stairs as quickly as his meaty legs would carry him. Walking felt weird, with his hips so much wider now, even though they seemed much stronger than before, the tail bobbing over his butt cheeks not helping matters at all. And this incessant itching on his chest and abdomen... James let go of his ruined pants with one hand to scratch one of the spots just below his ribs and yelped in surprise as he felt his fingers brush over a prominent, swollen nub poking through his shirt.

He froze halfway up the stairs, looking down his front in horror. And indeed, on his chest, lower ribs and upper belly, right were the six itching spots were, something tented the fabric of his shirt. Something that looked suspiciously like... hard... throbbing... nipples...

"HEY! No dawdling! Get changed and help me clean up," Lily yelled from the kitchen, reminding James that he wasn't in the clear yet.

Continuing up the stairs, James had to fight to keep his breathing level, trying not to freak out. This was definitely not normal. No amount of **** made people grow tails or extra nipples or... or fucking dog dicks! Because that was what sat in his crotch, nestled in a fuzzy sheath. Temporary swelling his ass! Lying to himself might have helped James not lose it earlier, but now his mental defenses were crumbling. James' mind raced as he moved towards his room - all his changes were easily hidden by baggy clothes, but what if they continued? That was impossible, right? Just growing additional nipples was insane already, not to mention the tail. Surely that had to be all that would happen, right?!

As James closed in on his room, the itching all over his front lessened - obviously a sign of the changes winding down. He breathed a sigh of relief: The tail could be removed surgically, the same was true for the nipples. As for the cock, well... the shape was unique, so there were bound to be at least a few women who would want to try that out, right? Maybe he could even become some kind of fetish porn star... The thought of rutting into a wet and ready female until his knot popped into her, locking them together until James spilled his seed deep within her hot pussy made his blood flow into his crotch, already running hot from his near-panic, James' pointed member twitching in its sheath. His nipples, too, throbbed and tingled as they rubbed against his shirt, making James drool as the exquisite sensations assaulted his brain, tongue lolling out of his mouth.

The finger that had been scratching at one of his extra nipples was now pinching and rolling the buzzing pleasure nub between two fingertips, sparks of bliss racing through James' body, pooling in his crotch. Already the red tip poked out of the opening of James' sheath, the knot widening and engorging along with the rest of the bestial rod. The last few meters were an ordeal for James, barely able to keep himself from just letting himself fall to the floor and milk his cock dry.