His cock begins to grow.

John groaned as his body began to heat up, his metabolic processes working in overdrive to fuel the oncoming changes. His groin in particular was getting hot, almost burning hot. Despite his recent orgasm, his dick stiffened up and rose to attention once more. Pinned in place by his reptilian beast of a mother, he could only watch as, slowly, his member swelled upward and outward. Growing slowly and steadily, it was as if his erection simply wasn't done. Inches added themselves to its length as the seconds passed. John's breath quickened with his heartbeat, half out of shock and fear, half out of arousal. He moaned from the sensation of his cock continuing to stretch out before him. It felt surprisingly nice.

"Yesssss, grow for momma..." cooed Julie, her mouth curling into an eager smile. John looked up at her monstrous, yet strangely recognizable, face. Her red eyes were transfixed on his rod, now a foot long and still going. John couldn't help but notice her fangs and tongue extend even longer as drool dribbled down them. Still in heat, the sight of his cock growing ever more massive excited her. Her lengthening tongue curled down around his dick, wrapping tightly but not painfully. Her eyes then met his as her smile widened.

Her tongue began to stroke his eighteen-inch cock, the coils sliding up and down as her saliva lubricated the surfaces. John moaned even louder. The pressure of his mother's serpentine tongue slowly increased as both it and his penis thickened. She picked up speed, stroking faster and faster. He was so close to cumming already.

And then he felt something warm and fleshy bump against his thighs. He didn't even have to look to know what it was. His balls had been growing alongside his two-foot member, and they were rivaling the size of grapefruits, filling the space between his legs. He could feel them churning as he was reaching his limit.

"Come om, boy, gib me your loab!" commanded his mother, her speech impeded by the thick tongue sticking out of her mouth. She moaned as her pussy dripped with anticipation. Her multitude of tits swelled out bigger and rounder, appearing to inflate like balloons. Each was as large as her own head, fighting for space along her torso. Even her nipples extended forward, resembling massive cow teats. They hung down low enough to brush against John's legs, which was impressive given his mom's enormous height. The sight of her even bigger tits swaying above him proved to be the tipping point. John's three-foot cock twitched, and his nearing-literal coconuts churning as his body prepared to unleash the biggest orgasm of his life.

"YESSSSSS!" cried Julie, sensing his approaching climax. Her head dove downward, her mouth sealing around his entire body, with the exception of his head. Her claws lengthened and her muscles bulged as her excitement grew. He could feel the heat and humidity of her breath all over his body as the tip of his cock hit the back of her throat. His body tensed up one final time, and he practically exploded. A deluge of hot, thick cum sprayed out of his engorged dick like a geyser, forcing its way down his mother's esophagus. His entire body vibrated as she let out a long, powerful moan.

"Mmmmmmhhhh!" Swallowing his hot load turned her on further, and her entire body grew even larger, her mouth now too large to even leave his head exposed. Were he not in the dark, warm cavern of her orifice, he might have seen thick, pointed spines erupt and ripple down her back. Additional, extra-sharp teeth sprouted beside her fangs, which themselves grew longer and thicker. Her body swelled with muscle, making even the largest body-builders look scrawny in comparison.

"MORE, MORE!" she roared as best she could. His body seemed to hear her and comply, his five-foot fire hose of a cock refusing to abate its blast. He could barely stay conscious through the ordeal. Four new pussies opened up on Julie's crotch, each with five new penises of their own. They all dribbled a constant flow of sweet-smelling nectar, able to intoxicate any nearby person and turn them into a willing toy. Her scaly ass cheeks inflated with muscle and fat, her butt big, juicy, yet nicely round. Her tail grew even longer in proportion to her body, the tip spouting massive spikes.

Finally, the flow of John's semen petered out as his basketball-rivaling testicles emptied. A cool breeze washed over his steaming skin as Julie lifted her mouth up and off him. She was absolutely massive. Her body towered fifty feet off the ground, while her mile-long tail coiled in a ring around them. Her new features only served to make her more monstrous in appearance. Part of him was afraid, but the part of him that did this to her couldn't be more excited.

"Lookssssss like the next effect hasssss taken hold," she said with a smirk, her thick, long tongue passing over her lips.