It was only a matter of time

“Thanks Doc!” She said leaning over and kissing him, finally making him blush, “Looks like you were worried for nothing Josh! I’m just a very special ‘little’ girl!” Josh smiled and began escorting her out. On the way out of the building Liz was skipping through the hall. “Hey, I think since I’ve missed so much school already, we might as well just go home.” Josh nodded, knowing what she might have planned, but also not thinking it was a good idea for her to go to school anyway. He turned on the car and drove home. When they got home Liz said that she’s up for a workout, and said if Josh wanted to join her she’ll be down in 10 minutes. Josh didn’t really want to be tempted, but he couldn’t resist another workout with his sister. So he got in his t-shirt and shorts and waited for his sister downstairs.

She came down the steps wearing pretty much the same thing, only she had the jersey tied up under her breasts and was now wearing panties. But the biggest thing was that her cock was no longer tucked up her vagina, but now filling up the front of her overstuffed panties and bulging out the front of her mother’s skirt. Josh sat excited as he watched her approach and do a wide double bicep flex. “Man I have gotten so muscular haven’t I? I still am not quite as muscular as you yet Joshy, but I think I’ll catch up very soon. Whaddo you think?” Josh just made an open mouth smile dumbly and sat up as she came closer. “How do you feel about that? Would you mind seeing your sister with bigger muscles than you? I know one part of you does…” she pointed at his growing bulge. “You just want me to be bigger all over don’t you?” She teased.

“Y-yes, Liz, you know I do.” Josh said, stopping Liz frozen as she heard this. She’s had his body tell her these things, but never his mouth. And it turned her on so much that her nipples snaped erect, blowing out of her shirt. “Oh my god!” Josh gasped.

Liz’s bulge in front began to enlarge as she closed her eyes. “Mmmm, I know you do. And I do too. Why don’t you show me how much you do. And now that the doc told us that I’ll shrink back down with out stimulation, you can grow me as big as I’m able to!” Liz invited just as her penis burst out of her panties. It was 15 inches and growing as it pointed higher and higher up. “will you make me bigger? Please?” She begged, and stepped forward to bump her cock against his face and slide to the side of his head as she ghasped. “Mmmmmmm, help your weak little sister get big and strong? I’ve spent all my life as a little skinny girl, and how can I become my brother’s fantasy that way?” She teased, instantly causing Josh to lose control and hug her dick. She quickly spasmed at the touch of her brother’s hands on her dick finally, and as soon as she felt his tongue on her shaft… “OHHH JOSH” she orgasmed, shooting gallons of cum up between her tits onto the ceiling. “Mmmmmm its never felt so goooooood” she said sincerely as she continued to cum, with Josh hugging and making out with her huge cock. Then the rumbling started, “s-s-stan stand b-back Josh! W-watch…” Liz managed to make out as she began her tremendous growth spurt. Josh stood back and adjusted his pants.