Mark pulled up the male vial and glanced it over. If these things filled up indefinitely, then he could become the manliest man in the world. He smirked to himself and grabbed a glass from the counter, filling it with water out of the tap. He then poured the contents of the male vial into the water, swirling it around a bit, before replacing the vial back into the box. Sure enough the light blue liquid reappeared in the vial, rising up to the top. He then repeated the procedure twice more, before he was satisfied with the amount of liquid in his glass.
"Well," he said to no one, still somewhat surprised at the deep sound of his new voice, "Down the hatch." He then chugged down the water in two or three gulps and waited for a moment to see if anything more happened. He didn't know if the male vial would actually make him more male, or if it would do nothing. After a couple of minutes he thought about trying some of the other vials, when he felt a churning in his gut. Looking down at his hands, he could see them growing larger, as the room around him seemed to get smaller. Or rather, he was getting bigger. Suddenly he was racked with a series of muscle spasms all across his body, as he felt every single fibrous tissue in his body flex and relax with a newfound strength. He watched as his biceps grew larger, becoming filled with untold strength. His chest ballooned out as his pecs grew massive, his shoulders becoming broadened and more defined. His abs transformed from a partially formed six pack into a rock hard ten pack, seemingly chiseled out of marble. His legs grew stronger too, and all across his body the fine down of hair that he had grown from his initial transformation become thicker, and more coarse.
"Oh fuck," Mark uttered, his baritone voice becoming a deeper base as he watched his face become more angular and defined. if he had to guess he now stood over seven feet tall and was covered in muscles. He grabbed his cock with his meaty hands and began stroking it, as the transformation began to center around his newfound sex organ. He pumped it faster and faster as it grew out from its previous six inch erect length, growing to a staggering foot long fully erect, with balls the size of tangerines to match. He grunted deeper as he felt a pressure growing behind his cock, and before long he jizzed out a thick stream of cum as his orgasm hit, splattering against the wall. He took a few deep breaths and then looked back at the vials, wondering what he could do next...when he heard a noise.