Seeing his son grow before his very eyes had led Adam's father to suspect that the amazing sports drink in the funny bottle was more than it seemed. He grabbed the skintight shirt that covered Adam's increasingly-muscular torso and tore it off, bringing it to his face. He could smell the strange potion on it, as well as some of his own cum. Somehow, that potion could make a man bigger... more than anything, he wanted to grow! He did not even recognized how insane that was--at six foot six and more than five hundred pounds of raw brawn, he was already significantly bigger than even the biggest professional bodybuilders! But his growing obsession was emotional and primal; it did not yield to reason.
Adam's hulking father stepped back, holding up the torn bits of shirt. He held it over his open mouth and squeezed, the muscles of his powerful forearm writhing under the skin as he crushed out all the liquid in the shirt and let it drip into his open mouth.
Adam watched in shock as his father drank more of the strange potion. There had already been two doses--what would a third do? And how would his father's pre-cum affect things? Adam was both worried and intrigued--he was concerned about what they didn't know about the combination of potion and pre, but excited about the possibility of the hulk in front of him becoming even bigger!
Awe filled Adam as he watched his father slowly begin to change. The man's height increased once again, adding twelve inches and making the towering brute a full seven-and-a-half feet tall. Muscle rushed to fill the newly-available space, already massive bulges growing freakishly, bloating with increasing amounts of powerful sinew. Adam's father let out a low groan of pleasure as he grew, his massive body trembling with excitement as it swelled to 900 beastly pounds of solid muscle. His hard cock throbbed, thickening and lengthening, growing until it was an 18-inch rod of thick, veiny sex. His avocado-sized balls swelled as well, doubling in size, their growth more dramatic than any other part of his huge body.
Adam stared up at his father, taking in the incredible height and breadth of the man, the sheer thickness of his freakish muscles, the impossible size of his outrageous genitals. The man was enormous to the point of being grotesque; Adam lusted after him terribly.
Clearly, the monstrous hulk was consumed by lust as well; his giant dick leaked a steady stream of clear pre. He let out a low growl of desire, taking a step toward his son, then another. The cum that had mixed with the potion had shifted the effects slightly: while the man got the added muscle size he craved, and then some, the pre-cum ensured that his sexual characteristics would be greatly enhanced as well. The big man's balls had become absolutely enormous and his libido had skyrocketed as a result. He reached out and grabbed the hunky young man standing in front of him. "Need this," the hulking man growled in a deep voice, pulling his son in close, wrapping his monstrous arms around the younger muscleman.
Adam could feel his father's huge dick between them, the oversized rod hot against his abs, the tip of it nestling between his meaty pecs. He cautiously ran his own hands along his father's sweeping lats, admiring their freaky thickness and the dramatic way they swept out of the other man's powerful torso. He did not resist when his father began to unbutton and unzip his pants, which had become uncomfortably tight and split in several places; rather, Adam helped his father pull off his clothes, eager to be naked. He moaned with anticipation as the big man picked him up and lay him down on the kitchen counter. He gasped as he felt his father spread his powerful legs and massage his ass, loosening it up.
For ordinary mortals, a three-foot counter would not have been the ideal place for sexual congress. For a seven-and-a-half-foot tall musclefreak like Adam's father, the height was just perfect. He pushed his giant dick into Adam, his insane strength forcing his son's hole to yield. He leaned over him, hands planted on either side of Adam's head as he began to slowly thrust, gradually opening up the smaller man. For his part, Adam could only moan as he was impaled on his old man's giant tool, and reach up to grope the giant pecs that hung tantalizingly close to his face. His father began to go faster, fucking him harder, driving that giant dick deeper. His enormous balls slammed against the counter over and over as he fucked Adam but he didn't care--it only enhanced his pleasure when his nuts were abused like that.
Adam let out a low moan as he came, his own big dick shooting cum all over his abs and pecs. His father didn't last long after that, roaring as he came, sending a giant load rocketing into Adam's ass. He wrapped his giant arms around his son and picked him up, using his freaky strength to lift him off of the counter and carry him over to the couch, keeping Adam impaled on his dick the entire time, filling him with more and more cum. Finally he lifted Adam off of himself, but only when he was certain that his dick was finished.