Ruben followed the other teen upstairs. "The rest is right down here! Come on in!" Chris said, as he opened the door and motioned Ruben to enter.
Ruben entered the room, it was almost more of an apartment, with a lounging room as the entrance, where 3 other teen boys were waiting for the party to start, sitting on beanbags.
"So yeah, this is my room, let me introduce you, these are my friends, Joseph, David and Billy!", Chris said, introducing his friends.
"Hi, I'm Ruben!" Ruben said, introducing himself, still kinda nervous about what he was supposed to do right now. He turned around, looking for Chris and gave him the voucher, "Here this is from us!", he said as he gave the birthday boy the voucher.
"Oh cool thanks! So, my parents are gone all day, so I hope you're able to stay 'till the end!" Chris said, inviting Ruben to come in further.
Ruben took off his coat and his shoes, and left them at the door, "So, what would you like me to be?" he asked Chris, not knowing how else to proceed...
Chris thought about it, as the others rose up from their bean bags in excitement, shouting all sorts of species, for Ruben to possibly transform into. However Ruben saw something about them that made him stop dead in his tracks. All he could do was just stare in confusion.
Chris looked at the new guest, then back at his friends, before it dawned on him... "Oh yeah, we are all, well it's obvious isn't it?" He laughed a bit as he put his hand on Ruben's back and pushed him in further, and then he pulled down his pants.
They were all wearing diapers, even Chris, who turned back towards Ruben.
"Would you like something to drink? We have enough!" He said as he waddled to his friends.
Ruben was kind off unsure what to do right now, as he just stumbled through the room, still clutching the changer.
"So you said I could choose the animal right?" Chris asked, finally giving Ruben something to change his mind to.
"Yes, that's right! I can use this right here to change into it, so if you have an idea, we can work with that!" He explained to the diaper boys, who were kind off busy with feeling each others diapers.
Only Chris kind off listened, "So you could turn yourself into, I don't know, we used to have pigs?" he said, kinda unsure.
Ruben had his answer. "A pig... Right, yeah sure", the boy set the portable changer on a table, finally drawing some attention.
He unlocked it, and adjust some settings. Ruben thought hard about it, what would he pick? He still has full control over what he'd change into, and to be fair, wasn't super determined to go all the way anyway.
With a whizz and a burr, the machine was done, as Ruben picked up the newly produced pill and quickly downed it.
He turned around, the 4 boys having him completely surrounded right now, all interested in what he just did.
"What did you just take?" David asked, being the first besides Chris to open his mouth. "Oh that pill? That is what changes me! It happens gradually, but it won't take long!" Ruben explained.
"Wait dude, take off your clothes then! We wanna see!" Billy jumped up and down, his diaper swinging between his legs. The other boys agreed.
Peer pressured, Ruben took off his clothes, leaving him with just his boxers, but the boys weren't happy with that.
"Dude take it all off! What if you are getting a tail, we wanna see!" Chris said. "It is my birthday after all, and with how the day is going, good chance you'll see us naked as well too!" he added, as he tapped his diaper.
Ruben didn't really know if he should, seeing how he did activate the genitalia option...
He thought about it for a bit, and caved in, dropping his boxers, he stood there now butt naked as the other teen boys cheered.
That was also when Ruben finally felt something happening, as his nose started to feel funny.
The other boys watched in awe, as Ruben's nose flattened, and angled upwards, forming a pig's snout.
The boys gasped in unison, touching the snout gently. Ruben oinked, spooking the boys, who quickly started laughing.
Maybe this wasn't so hard after all!
It didn't take long for a weird sensation to arrive at his ears either, as they grew pointy and formed floppy pigs ears, after that, a curly pig's tail, grew right above his butt, and his skin turned pinkish.
"Dude you look adorable!" Joseph said, whilst playing with the pig boys tail. However, everyone's focus of attention soon changed, as Ruben's cock started to rise and twist into a corkscrew like shape, and grew a couple inches longer.
Ruben stood there grunting a little from the pleasure of his shifting cock, not sure how the others would react.
The diaperboys looked at eachother in silence, and then started cheering.
Ruben grunted out a laugh, as he was pulled towards the center of the room, almost tripping over as his feet turned into trotters.
One of the boys, David, pulled off the tapes of his diaper and quickly grabbed his own dick in his hands, as did Chris. Billy and Joseph sat on top of eachothers diaper and started humping eachother.
Noticing their little piggy, just standing there, Davind and Chris pulled Ruben down, and David wrapped his hands around the corkscrew shaped cock, and started thrusting his hand up and down.
Ruben squealed in delight, his cock throbbing in the palm of the others hand, as David kept pumping and pumping.
It didn't take long before a pressure built up in the tip of his cock, and fresh pig semen flew through the air.