"Wh-what are those?", the kid was eyeing the content of the small plastic bag - a couple of white shirt cuffs and a matched shirt collar complete with a black bow tie. "A-and how can they help m...".
"You should try them on", you interrupted him in a jovial yet firm tone. "Consider them a gift. I can guarantee you they will help you".
"O-okay". The boy opened the plastic bag and put the cuffs and bow tie on. He was wearing a t-shirt and a pair of baggy pants, so he looked pretty ridiculous.
You looked at him, pensively stroking your beard stubble with a finger. "You should really take your t-shirt off, kid. It doesn't suit you right now".
"If you say so", the boy replied, in a slightly firmer, deeper and more mature voice than before. He readily took off the t-shirt, letting it fall on the floor, where it disappeared into thin air a couple seconds later. The boy didn't even realize the strange happening: he just stared at you, expectantly.
You took a long look to his chest and arms, pale and scrawny. "This is going to change soon", you thought, smirking inside.
"U-um... So, what do you think?", the boy asked. He already looked a couple inches taller, and his hair were slowly but surely straightening out and growing, even getting some blonde highlights.
"I think you're doing fine", you replied, getting closer. "But you're still not trying hard enough, if you know what I mean".
"What do you m...", the kid started asking, before you placed your hand on his crotch and started to skilfully rub his cock through his pants and underwear. The kid let out a surprised moan, and a blissful smile appear on his face. In a matter of seconds, you felt his young dick coming to life under your fingers. "Yes, this is the hardness I was talking about".
"D-don't stop", he begged you, trying to wrap his still slender arms around you and stretching his neck to kiss you.
You, however, gently push his face away. "Sorry, kiddo, you're still not manly enough to aim for the taste of my lips. Concentrate harder, became what the cuffs and the collar are telling you to be...".
"Y-yes...". His hair were now a proud, thick, blond mane. His stomach was now completely flat, with a nice, perfectly-shaped four-pack hardening by the second. Under your hands, you could feel his boxers turning into the skimpiest thong, while the texture of the pants started warping and shrinking, not to mention becoming smoother; less than a minute later, the growing kid was now sporting a gorgeous pair of black leather pants that looked like they had been sprayed over his muscular legs and thighs. His cock was now way bigger than before, and if your fingers were correct - and you know they were - it was also sporting a thick Prince Albert.
The upper parts of the kid's body was of course growing accordingly: the four-pack was now a six-pack, and his pecs were juicy slabs of meat; you pinch one of his erect nipples with your free hand, eliciting a deep, manly moan from his now puffed-up, kissable lips. "F-fuck yeah...", the young man whispered in his ecstatic daze; he extends a rapidly darkening hand and reciprocate the favor with your own already rock-hard dick, and you let him do that. A rich wave of bronze emerged from the inside of his pants, enveloping the entirety of his skin with a dark, sexy tan that made him look like he was made of brown leather.
Any adolescent blemish was instantly cancelled from his face; his chin became squared and virile, his eyes shifted from muddy brown to a light, enticing shade of green, his teeth were regular and pearly white and a pair of huge, polished diamond studs now adorned his earlobes.
The only thing left to change were his arms, that still looked scrawny and totally out of place on his now buffed up, sexy body. You decided to gently caress one of his arms to experience the last part of the changes first-hand: and surely the sensation of muscles contorting, expanding and getting the workout of a lifetime in a matter of seconds nearly made you cream your designer pants.
The newly-made Chippendale dancer looked at himself, marveling at his transformation. "Thanks, dude!", he exclaimed with a cocky grin on his macho face. You let him come closer and slide his hot, soft tongue inside your mouth, filling it with pleasurable warmth.
After a brief yet intense French kissing session, the shirtless hunk stared at you with his mischievous, yet strangely innocent green eyes. "So... What about me sucking your dick? You know, as a way to repay you for all this".