I guess we'll never know if we don't try...

As her shadow eclipsed him he started to back up fearfully, then noticed something as a steady stream of precum flowed from her cock. Her breasts were straining the sheet, and her spandex were letting out sounds of stretching. “Liz, your sheet is looking too tight!” Liz smiled and undid the back, letting her nipples spring forward, flinging the sheet forward at Josh.

“There, better?” She smiled, still slowly walking closer.

“No LIZ! You’re getting bigger!” He yelled, but Liz didn’t react, other than to bend over to pull off her spandex. She stood straight up several inches higher than a minute ago, and then stretched, lifting her mammoth breasts high above his head, her hard, long nipples trickling slightly more milk than normal. “You are so fucking amazing, I can’t believe you.”

Liz grinned and dropped to her knees, now a full head taller than him there, then sat back on her feet. “Stick that tiny dick of yours in mine big brother, and watch me become the biggest, sexiest, strongest person in the world.” She panted to him, sweating heavily. She put her hand on the top of her cock and aimed it at his crotch, by now it was half a foot longer and a full foot thick. Josh dropped his pants and Liz gasped in victory, growing sharply as a spurt of precum shot out. Josh approached, his sister’s head slowly rising to his. He went for it.

Surging forward he thrust his 9 inch erection into his sisters now 40 inch erection. Liz bellowed loudly and leaned back on her elbows, arching her back and lifting her brother into the air with her cock. Her growing breasts were sticking out slightly off to either side, large and taut, and he could just reach her nipples to stabilize himself. Liz gasped and her nipples grew in his hands, filling them, his hands covering the tops like he was holding a doorknob, milk spurting out of the sides of his palms. Liz could barely hold on any longer as she began bucking, and each buck Josh felt himself lift slightly higher into the air until half a minute later she thrust as far as she could and bellowed in a loud cry “OOOOAAAAAAHHHHHHHHH!!!” Liz’s nipples erupted with such **** Josh’s hands blew off them, and he had to grip her large cockhead to steady himself, it was vibrating so wildly he couldn’t hold back and came inside his sisters cock, moaning, which his sister felt and triggered her. “OHHHHHH JOSH MYYYY GODDD!!!” Liz felt a hot magma **** brewing violently in her groin and stretched out her arms screaming.

*KABOOM* her cock erupted shooting Josh off her sisters monsterous cock, throwing him to the floor behind her, knocking him out. Liz was arched on her shoulder and her shins with her knees bent and spread, her body arched violently in the air with her hard cock pointing behind her like a petrified firehose, continued to spay her impossibly large load into her poor **** brother, for minutes it went on as she continued to grow bigger and bigger the entire time. Her arms swelled faster and larger than ever, her pecs lifted her breasts further from her rapidly enlarging barrel chest, her ass grew rounder and fuller, her legs growing so thick they were pressing her bent leg apart. Spraying also in increasing torrents was her larger than ever nipples, impossibly long and spraying gallons of milk in such an intense torrent as to cover the ceiling, splashing down on the ground onto the already fully soaked mats. And still she came, growing and growing, impossibly huge, until the flow of cum slowly died, and her body relaxed. When the flow finally stopped Liz was laying spread out, arms and legs extended, and her cock limply relaxed along her chest, its enormous head resting on her **** face. Neither could predict what waited for them when they awoke.

Josh woke up on the couch in the living room. His clothes were changed, but his skin felt filmy and his hair was stiff. He got up and wandered the house “Liz? You there?” He called. He barely remember the events before he passed out, but knew that Liz orgasmed again, and was eager and frightened to find her quickly in anxious anticipation. How tall was she now? 10 feet? Her breasts must be the size of beachballs by now. He slowly descended the stairs to come upon the milk and cum soaked rec room. The mat squished beneath his feet, he stood dazed as he stared at the damage. Lost in thought he got startled as he felt a giant hand firmly grip his shoulder, as another patted his head, before softly resting on it.

“Hi little brother, sorry about the mess. Think you could help me clean it up?” A loud voice said.

Josh was startled and a little scared by what was waiting behind him. He tried to turn, but the large soft hands on his shoulder and head effortlessly kept him in place and from looking up. “Liz, is that you? What happened? You okay?”