Finding your way back to the front, you go to check out, and the cashier is just doing menial work when you approach.
He asks if you found everything okay, but as he sees what you're holding, some odd notion of fear begins to dawn on his face, rising to the surface extremely quickly.
"... Where... where did you find that?"
"This dusty old flashlight? Just in... one of the back bins of cheap stuff."
"They put it in there? Why would they put it in there. Did the guy not know what it would do?"
You were starting to be weirded out, but things only got weirder with what happened next.
As you reached to place it on the counter for the man to scan, he began reaching for it in a way that indicated he wouldn't let you buy it. Not sure what he was so afraid of, you said, "just let me buy it, it'll be out of your hands if you let me take it." As the man pawed for it, he clearly was not interested in the offer, and said, "You don't understand... if this gets used without a way to fix everything in place... it could get out of hand very quickly." Not knowing what an anthro slob is, you continue pushing him to let you buy it, and the two of you begin tugging lightly on the switch.
After a couple of minutes of arguing back and forth, no one in the shop, you start to fill with ire, and curious why the shopkeeper was so extremely frightened of a small, rickety, decrepit flashlight, you turned it on.
As the cashier was awash in the pale green glow, confusion, followed by a realization, turning into horror as his skin slowly started changing, growing hairier, and morphing.
"What... what did you do?"
As he says this, his body quickly starts piling on lard, and as you release the pressure on the light, you discover it won't turn off. As the cashier bathes in the light more, he starts moaning, saying, "Hope... you...". He begins masturbating, a large cock unsheathing as it bursts out of his clothes, now looking more... porcine in appearance. As his hand wraps around the massive new cock, it begins to morph into a mutated combination of a boar's front hoof and a human hand, nails turning pitch black. His belly also begins expanding as he stutters out even more of this thought "know... what you're...", the transformation happening so quickly, yet so fundamentally new to you that it seems to stop time. His nose turns upwards as his mouth extends forward, and you finally gain enough control of your body to begin backing away. As his mouth joins to his nose to form a new piggish snout, tusks emerge. He's turning into a boar, a thought that you finally realize as he finishes. "...doing with... that thing..."
His hair then proceeds to almost animate itself, curling up away from his head before diving into his skin, quickly leaving him almost bald, as hair bursts from across his body. The cashier begins belching and farting intensely, each gaseous emission making the stench in the room worse, and within moments, it's clear that his transformation is complete when he ejaculates this disgusting, yellowish seed, and the light turns off. For just a moment, he seems not to notice you, before he turns to eye you.