Robert had no idea what was going on or how in the world those girls had gotten so big, but it was clear that the weird gun Sarah was holding was a big part of the puzzle. Sarah was turning some dials on the side of the device and Amanda was grinning an evil grin. There was something in that smile that made the hair on the back of Robert's neck stand up, and suddenly every mean or crummy thing he'd ever done to his sister went running through his head. Robert knew that if Amanda grew to be even half as big as either of those girls he was in big trouble. And from the looks of that smile she was going to be even bigger than her friends. He knew he had to think of something and quick. 

Sarah was finished making her adjustments and was taking aim at the skinny teen who anxiously awaited the transformation that was about to occur. Just as Sarah was about to pull the trigger Robert grabbed the only thing nearby (a half filled water bottle) and threw it at Sarah's head. He began to make a dash for where she stood and just to add to the confusion shouted, "Look out."

Had she been a giant for a few weeks now Sarah might have been comfortable enough to just allow any old item bounce off her super-strong body. But since she was more used to being a small and somewhat weak girl her reflex was to duck away from the incoming movement in the corner of her eye. That flinch gave Robert just enough time to make a grab for the gun. He took hold of the barrel and attempted to yank it out of Sarah's grip, but she was far too strong and he had no chance of breaking her hold. In the midst of the struggle, though, she inadvertently pulled the trigger and the yellow beam of light discharged directly into Robert's chest. 

By this time Bethany had stepped over and gave Robert a shove causing him to spill onto the floor. All eyes were on Robert as he began to get back up. He paused when he was on all fours and watched as his arms began to swell larger and thicker. His entire body was pulsing, his T-shirt had been loose moments ago and was now pulled taut around his rapidly expanding back. The fabric began to pop and snap as the seams were overwhelmed by the force of Robert's giant shoulders and lats. Then a rip formed right down the center of the back of his shirt and his muscles were allowed to breathe free at last. 

Robert got to his feet and found that he was now the tallest person in the room, and by a rather substantial margin. He guessed his height was now somewhere around 6 feet 9 inches, but it was his mass that was truly impressive. He pulled the tattered remains of his shirt off and tossed them to the floor. No sooner had he taken care of his top when his shorts ran out of room and began to split up the sides. One quick move and he was clad in only his white briefs (which were also straining to hold on as his member had gotten in on the growth action and had stuffed his underwear to overflowing).

Robert's had eclipsed Sarah's girth and was still growing. His enormous chest blocked his view of his lower body, but when he raised his arms and flexes his biceps the muscles that exploded upward clearly outmatched her 30 inch guns. 

Amanda had seen enough. She was not about to let her brother steal her spotlight again. She went to Sarah and took the gun from her meaty hands. Amanda knew that she'd have to set the gun to an even higher setting to outgrow her brother and keep him in line. The idea to shrink him back down never even occurred to her, and that would be her biggest mistake. 

Robert watched as Amanda adjusted the dial on the side of the gun. There was no question in his mind that he would be able to get the gun from his tiny sister now. His muscles still slowly swelling he walked to where she was. Amanda pointed the gun at herself, but just as she squeezed the trigger Robert's giant and wrapped around the barrel of the gun and the full discharge of energy emptied into him.

"NOOOOOOOO!!!!!" Amanda screamed as Robert liberated the gun from her hand. 

For a moment the girls thought that they were going to be okay, because the first thing they noticed was that Robert seemed to be getting smaller. Even Robert was a bit dismayed at his reduction in size, though he had to admit he felt stronger than ever. As it turned out he had nothing to worry about because while he was still growing larger his muscles were very rapidly becoming denser and packing much more muscle into smaller spaces. His sinew quickly reached the density of Kevlar, then granite and finally the hardness of steel. Living, moving steel. By this time Robert had reduced down to the size of a middleweight bodybuilder, but as he began to realize what was going on a smile crept across his lips. Much like the grin that his sister had worn earlier, this one made the girls nervous. 

Robert tucked the gun into the waistband of his underwear. "Oh, here it comes," he said closing his eyes and raising his arms, "I can feel it." Just as quickly as it had contracted his body began to expand once again. Within seconds he outgrew Bethany then Sarah. He was packing on gobs of ultra-dense, super-strong muscle so fast that everyone could hear the tight muscle fibers rubbing against each other as they fought for space on Robert's widening frame. He clenched his fists and curled his arms inward in a huge most muscular flex as he did he roared with enough force to vibrate the walls slightly. Then he put his hands on his hips and flexes his gigantic chest which was now dense enough to easily stop bullets. His pecs looked like they were going to rip right through his skin. Robert's shoulders were five feet wide and the arms that hung down from them were bigger around than his torso had been before his insane transformation. As he surveyed the room he realized that he'd grown taller once again and was now around 7 feet tall. He flexed his thighs enjoying the feel of them swelling and shrinking as he tensed and relaxed them, though he couldn't see them he knew they were titanic since he had to stand with his feet slightly apart just to give them room. At last he lifted his arms up and flexed his mighty biceps. As he tightened his fist and tensed his arm the peak of his huge muscle rose and rose. Robert cried out with effort as he squeezed every last inch out of his flex, willing the top of his bicep higher and higher until the peak crested several inches higher than his hands. His enormous arms measured a mind blowing 54 inches around. 

"Well," he said in a deep voice, "it looks like I got the prize after all."

"You bastard!" Laura shouted and she charged her behemoth brother, pounding on his thighs and stomach. She quickly stopped though since punching him was like punching a mound of steel. 

Robert smiled, grabbed Amanda by the hand, and lifted her high into the air so that they were face to face. "I get it. You wanted to turn into She Hulk and teach your younger brother a lesson but now he's the biggest and strongest person to ever live. You can be pissed if you want, but it won't do a bit of good. I could knock Superman on his ass; what chance do you think you have? Now, you and your amazon friends are going to leave and maybe, if you're good, I'll buff you up as a gift later. For now, scram!"

Robert tossed his sister through the air into the arms of Sarah, who caught her easily and set her back down on the floor. Amanda looked like she was about to say something but decided against it and instead turned and left the room defeated. Bethany and Sarah followed behind. 

When the trio of boys were alone once again Robert pulled the gun from his waistband and held it up. "Well fellas, who's up for some real strength training?"