The transformation had made Jess incredibly horny. Pussy juices flowed liberally down her titanic thigh as she stroked Robert’s much improved manhood. His erection inflated to nearly 10 inches under Jess’s expert ministrations as he sat on the edge of his bed.

“Hmmm, that looks pretty nice” she said as she straddled his penis. From his lying position all Robert could see was Jess’s immensely wide back, and the edges of her titanic breast protruding at each side. He was mesmerized by the tempo of clenching and unclenching of her granite hard glutes. Robert grabbed her by her tight waist and added to her movement.

The sight was unbelievable to Amanda’s eyes, Jess’s gigantic muscular form gyrated up and down the length of Robert’s pole. Her huge tight muscles writhed and clenched in a rhythmic fashion. It seemed as if Robert’s penis was about to burst through it’s own skin so enlarged was his organ. But because of Jess’s intense vaginal clamping, he was unable to cum until she let him. Jess kept riding and grinding on Robert for a few more minutes, all the while caressing her massive muscular form, her hands alternated between fingering her clitoris and grabbing the enormous firm globes that were her breast. Every once in a while she would grab her taut ass and contribute to the undulating movement with her massive arms.

Amanda was thoroughly transfixed by the rhythmic spectacle of muscular perfection.

“That’s pretty good Robert, but I’m a BIG girl, you’ll need more than that to satisfy me. Let’s move this from good to great” Jess declared in between deep breaths.

Jess took the gun, adjusted the settings a little and fired straight at Robert’s cock.

Instantly the organ was animated with new vigor. Large veins appeared on it’s surface, it’s diameter appeared to double in a few instants. The massively enhanced organ somehow still fit completely inside Jess’s titanic body, but it was obvious from the change in her facial expression that it was now reaching parts of her insides that were not being stimulated before.

AAAAAHHHH! MMMMMM! AAAAHH! Jess cried, barely able to contain herself anymore. Aside from enlarging Robert’s member, some of the gun’s blast had spilled over to her cuntal folds, their sensitivity had more than doubled.

Amanda was mesmerized by the size of her brother’s organ. In between Jess’s thrusts down it length, she could see it was longer than a foot in length and easily 4 inches around, much bigger than her own forearm. It was encased in a thick throbbing network of veins, their irregular surface apparently much pleasing to Jess.

Robert’s body had also grown somewhat from the gun’s blast, it was apparent to Amanda that his leg muscles had swelled slightly larger and their definition increased, but the vast majority of the growth seemed to have gone directly to his penis.

MOOOORRREEE! Jess cried as she zapped Robert’s already massive organ once again.

This time it was too much for even Jess’s massive muscular form to contain it all. In a few seconds Robert’s organ grew to 2 feet in length and 6 inches in diameter. With it’s increased girth and length, combined with the Jess’s further enhanced cuntal sensitivity, it only took 2 more thrusts of the massive appendage to make Jess cum with an incredible fury.

AAAAAAAAHHHHHHHH! Jess cried as her massive muscular form contracted every muscle fiber simultaneously, her abdominals convulsed with deep contractions along with her vaginal muscles. With each contraction and relaxation, vast amounts of clear whitish liquid were expulsed from Jess’s throbbing vagina. Robert’s massive organ was pumping massive amounts of cum into Jess’s gigantic body just as she was ejaculating what seemed like liters of pussy juices.