"Wait, really?"
"Yes, really!" Mike laughed. "This is amazing, it goes totally beyond any realm of science, theoretical or not. We'd be idiots not to use it, for science and fun."
"Yes, I knew you were a cool dad!" Jeff cheered, hi-fiving his father. "Do you want to be the test subject?"
Mike raised an eyebrow. "I'm taking that to mean you already have an idea in mind."
"Well, something like that. I thought, if you want to run tests, ae might as well have a lab rat. Not a metaphorical one, though," he quickly added and watched his father's eyebrows shoot up. "I kind of wanted to see you become a literal rat. And then we can experiment on you."
"As a man of science, I am always willing to put myself on the line for the sake of a breakthrough." His eyes twinkled. "And as your father. I want to do whatever makes you happy. So, go ahead and zap me, son!"
Jeff quickly navigated the options. "Alright, I'm changing you into a rat, but I'll keep all of your human intelligence, okay? You'll still be able to comprehend language and whatnot, you just won't be able to speak." He didn't mention that he'd still be tweaking his dad's mind to remove all his reservations. He would love anything Jeff did to him and even crave more changes.
"Alright," Mike agreed. "Though I am curious as to how a rodent brain could store- oh!"
Jeff had already pressed enter, and Mike dropped a foot in height. He gripped the bed to stabilise himself, only to realise claws had begun to appear on his fingertips. He shot down another foot, then another, as his limbs began to recede and set themselves into strange, inhuman shapes. His nose began to twitch as it extended into a blunted snout, tipped with fine whiskers. Clothes began to transition into soft white fur as two large ears extended from his increasingly rodent-shaped skull. Now barely a foot tall, he fell to all fours, writhing on the ground as he continued to shrink. Squeaks came out of his mouth, his teeth now perfectly suited for nibbling, and a long tail extended from just above his rodent anus. As the transformation ended, he sat up on his hind paws and looked at his son.
Jeff looked down at his little white lab rat. Scooping him up, he placed him on the desk beside him. "Isn't it strange," he mused. "A minute ago, I wouldn't have been able to move you an inch, and now I can hold you in the palm of my hand."
Mike gave out a squeak, one which Jeff took to mean, 'I can hardly believe it too'. He chuckled and turned back to the computer. "Now, what shall we start with?"