24 year old Matt Johnson smiled as he looked at his twin sisters Brittney and Becky, both of them 18 and in their final year of high school and both of them blond bombshells compared to his nerdy build and dirty brick red hair. Their parents had just left for a extended cruise that would take at LEAST 2 months, if not longer and knowing the type of girls they had raised they had called Matt to come and spend the summer supervising his sisters. 
Matt while being the weirdo of the family and semi exiled, was well know to be a mature and responsible young man hence why his parents hadn't helped him at all with collage, making him scrape and fight to make his way and he now held down a modest though low level tech job. 
His sisters meanwhile were party animals and cheerleaders, who's good grades were well know to almost every one (Save the principle and of course their parents) as being the result of the girls getting down on their knees or blackmailing the teachers. That wasn't to say that the girls weren't smart in their own ways, having a knack for finding out and digging up dirt on anyone they needed to. and of course if someone was squeaky clean, they weren't opposed to making dirt as a matter of course.
As a result of the conflicting attitudes and the fact their parents had already ensured the girls would be looked after for life with trust funds ready and waiting on them, was it any wonder the twins and matt didn't get along? Still, he was looking forever to looking after them while he got to live it up in the mansion his parents owned, planning on becoming better friends with them and also hopefully teaching them the value of a honest days work. The girls for their part.. had other plans and waited for mommy and daddy dearest to be driving away before putting their plan into action. 

"Sooo Mattie.. Still working those double shifts to keep the lights on?" Brittney asked, coming over and smirking, though her perfect little nose wrinkled a bit at the slight smell coming off of the loser. 
She was dressed in tight jean shorts and a white halter top that had the power to make nerd cream their pants (a fact she had proven more then once) and distracted the dweeb of a older brother while Becky went to work, making Adam one of the twins trademark drinks: the voodoo blackout special. 
All the fun of the target being on auto pilot and not knowing what their doing plus the joy of getting them to follow commands as long as you kept it simple.
"well yeah, if you have to know, they hiked up my rent recently even though we had a infestation of roaches. works out I'll be staying here for awhile while they spray." Matt said, raising a eyebrow and not quiet trusting Brittney. "Guess I could use a shower."
He went to put his bags down and leave only to find Brittney cutting him off, a clearly fake smile on her face. 
"Oh no, it's ok.. after all, what's a funky smell or two between siblings right?" She asked with a wink. 
"..Ok what do you want?" matt asked, folding his scrawny arms over his chest.
"heh, Saw though the nice act huh?" She asked, feigning defeat as Becky came over with a glass of flavored water for her Brittney, and something a wee bit stronger for Matt.
"we wanna have a small little get together with our friends and take advantage of the pool and daddies wine cellar to do it." Becky said, handing Matt his drink which would look and taste just like the girls. 
"And by a small get together you mean half of the school, tearing it up and getting wasted." Matt said, sipping his drink and finding it oddly nice despite normally distaining flavored water, and having anther drink. "Not to mention that the legal drinking age happens to be 21, not 18." 
"Awww, come on Matt, you don't want to make the two most popular girls in school look like a couple of nerdy losers do you?" Brittney sulked, giving him the puppy dog eyes. 
"Yeah, plus they'll be a TON of hot girls around for you to oggle, not to mention boys." Becky giggled, winking. 
"Oh ha ha. I told you guys, I'm not bi or gay!" Matt huffed, feeling a little flustered and squirming, taking a BIG gulp of his drink now.
"really? is that why there are still legends of the blow job prince floating around the school?" Becky asked, snickering. 
"Your still the third most popular cocksucker, at least behind us." Brittney added.
"L-Look! I told you, I wasn't doing that by choice.. the football team would corner me and.." Matt huffed and whined, even as he started to make a tiny tent in his pants and the edges of his vision were starting to go black. "Look I said no! and teasing me isn't going to help!" he squeaked out, finishing the rest of his drink and standing up to leave. 
"Heh, wrong choice dweeb. Just remember, everything that's about to happen, we DID try and give you a chance to play ball." Brittney said, then pointed back at the seat. "sit."
Matt went to tell Brittney off but found himself sitting back down as his vision got worse by the second.
"W-What.. what did you two.."
"Just relax dweeb. we're not going to hurt you.. too much. after all, we're family." Becky snickered and her and Brittney's laughing faces where the last thing Adam would see before his vision went blank.

it was dark out as Matt woke up, his head pounding and there was loud music playing somewhere in the house. he was on a bed in the guest bedroom, or so he assumed from the faint light coming from the street lamps as they illuminated the tacky paintings that his mother insisted in putting in the said guest room and Matt slowly sat up, putting a hand to his forehead and groaning, only to freeze as he A) heard a lot of weird crinkling and crackling and B) the hand he put to his head was covered in a soft mitten of some sort. 
A quick glance down would explain the crinkling and cackling, though it wouldn't make the young man feel any better as a bright blush took over his face, if anything it made him feel worse and his guts rumbled and gurgled from his nerves, or so he assumed. 
he was wearing a pair of latex knee highs that appeared to be hot pink in color, those the street lights didn't provide enough light for him to be a 100 percent sure, but he could tell that they had some form of a locking band around the top from how tight they clung to him as well as the little padlocks that jingled softly as he looked. 
he also had a locked pair of black high heels on his feet, with what little like at least 4 inches for the heels themselves, no doubt a effort to keep him from walking. 
His hands were indeed trapped instead of mittens that matched the color of the knee highs, with them locked at the wrists and making it clear even if he hadn't of been locked in, he'd of been helpless to try and remove anything himself.
His outfit was a latex and plastic baby dress, hot pink (again if he was reading it right) with a white trim and a quick though noisey check confirmed he had the puffed out shoulders and everything, meaning he was indeed dressed like a little girl and assumed that he'd found a lock on the back of the dress if he so bothered to look.
Of course the biggest factor in cementing that he was being dressed like a little girl would of been the massive, almost cartoonish sized diaper between his legs, making any effort to bring his legs together futile and of course covered in a locking pair of plastic panties that were black shockingly, and keeping him from seeing what color his huggies might of been as well as trapping all heat around his privates meanwhile he had some epic swamp ass going on. 
A final insult, or maybe just a after thought was the baby bonnet he felt on his head, unable to see it due to the lack of a mirror in the room but feeling it so to speak and noting that it wasn't locked on, though it wasn't like he had use of his fingers to undo the bow under his chin. 
turning and twisting around on the bed, the humiliated young man got to his feet and went to storm towards the door, when the combination of the heels and the massive diaper did him in, making him face plant onto the thankfully plush carpet and groan. 
"they think they can just drug me and dress me like this! Ha! I'm gonna storm out there and...and.." Matt raged and ranted, only to realize thankfully soon enough to save himself.. just exactly how he was dressed AND the fact it was a house full of drunken 18 year old's out there, no doubt all of them having cellphones and more then ready to make him a internet meme.
"...they have to come in here at some point, and when they do!" Matt promised himself, though he still crawled over towards the door and got himself pressed against it to keep anyone from coming in and catching him in all his baby girl glory. 
Having to listen to the trash that these punks called music and getting dry mouth not to mention being hungry, Matt couldn't picture the night getting any worse then it already was and tried to lose himself by picturing just what he was going to do to his sister, rocking back and forth as tummy cramps started to build, with him playing them off as hunger pains despite the growing urges building in his behind.
10 minutes later (though from his POV it felt like HOURS) and there was no denying what was happening, Matt had a massive dump on deck ready to come out and even if he could get to a bathroom, the diapers were locked around his hips and somehow he didn't picture his sisters would be kind enough to unlock them and let him use the shitter after all the trouble they had gone to getting him dressed. 
getting up on his hands and knees and trying to find a position to ease the cramps, Matt made the mistake that many before him and many after tended to make when trying to hold in a epic dump: he assumed if he could just let off a little gas he'd be ok. Of course as anyone who's ever ended up in a ruined pair of undies could of told him, all it takes is the smallest crack for the dam to break.
Hence how one small fart turned into a massive wet and sputtering one and then the back  of Matt's big diapers got a bit better as his own sludge started to fill them, making the big helpless bondage sissy baby sob and whine and suck on a mitted thumb, tears running down his cheeks even as a perverse level of pleasure kicked in from being able to get it all out of his tummy. 
Not helping matted was the fact the plastic pants or panties, whatever you wanted to call them, were semi too tight and didn't let the diaper expand as much as Matt would of hoped in the back, and all too soon the sludge was filling up the front of his bulky diapers.
" *sob* ..this i-isn't right.. a-and.. it's not fair!" he whined to himself, his stench burning his nose but he knew for a fact that the windows couldn't actually open, his mom had gotten paranoid after a friend of her had been robbed from someone getting in a opening window on the third floor of the friends house.
"I-If only I had.. Said yes to the girls..I-I could be having my weenie in a cute girl.. not.. being.. surrounded by.. POOPIE!" he whined and then started to full on bawl, plopping on his mushy butt and rubbing his cheeks, kicking his legs and forgetting all about trying to stay unnoticed. 

Downstairs the music stopped JUST long enough for Brittney and Becky to hear the fit and the twins exchanged a look before draining their cups of vintage wine. 
"Sounds like the babies awake." Becky smirked.
"And just in time to provide some entertainment for the party." Brittney added.
Laughing the twins locked arms and made their way up the stairs to go and fetch their brother, knowing that as fun as the party had been, it was about to go to a whole new level.

The end?