A odd fact not known to many, as it turned out your normal run of the mill wizard was actually quite easier to put under trance and implant key words even with only a basic knowledge of hypnotism.  This would be a fact Harry discovered to his delight having gotten interested in it over the course of a summer and trying it out for fun on the train ride to Hogwarts.
Of course with him using it on his friend the triggers were just harmless ones, like every time Ron would hear a five sharp knocks on a door he'd bark like a dog, Or Hermione becoming a stereotype ditz if she was offered bubble gum till the flavor ran out. 
He also quickly removed said trigger once they got to the school and erased the memory of the act of them ever being in place. 
However, encouraged by the success of his little experiment, Harry would slowly work his way up with more and more amusing/twisted triggers on students he wasn't all that fond of till he came up with the perfect set for one blond haired prat: Draco Malfoy.
Getting the blond twat monkey alone to work his mojo hadn't of been easy, but once it was done and Harry had removed the memory of the triggers even being place, it was time to sit back and have some fun.  Still Harry tried to at least be semi fair about it, and promised himself to only use his new found powers if Draco was being a true and utter pain in the backside. which, again, this was Draco we were talking about, only took all of a day from the planting. 

"ugh, did somebody cut the cheese?" Draco asked, walking into the dinning area and moving pass Harry, Ron and Hermione.
He paused and then leaned down, taking a over the top sniff of Ron and then held his nose. "oh guess not, it's just a weasley!" He said and laughed, prompting his two loyal thugs to laugh with him even if the dim look on their faces meant they didn't get the joke. 
"really? reduced to making fart jokes Draco?" Hermione asked and rolled her eyes, moving in a bit closer to Ron and then wrinkling her own nose. 
the red head had skipped a shower after practice that day and well, did smell a bit ripe. 
"Ha! See? even you think he stinks!" Draco crowed and hooted with laughter. 
"You know Draco, it's not nice to tease others. Ron will smell fine once he gets a shower in but YOU'LL always just be a 'dirty boy'" Harry said, sipping some pumpkin juice and smirking.
"Really? thats the best..you..got..?" Draco scoffed back but suddenly he felt weird and found himself starting to pop a squat.
"ah..what are you doing?" Crab asked.
Draco went to answer with his mouth, but a blast of ass gas from his rear handled the reply for him and then as his thugs looked on in disbelief and Hermione and Ron and Harry looked on with amusement, the back of Draco's jeans started to puff out as a horrid stench filled the area.
"Is he crapping himself?" Ron asked, laughing and pinching his nose shut.
"N-No! I'm not a stinky baby pants pooper!" Draco whined and then even as he was clearly fighting himself, he popped his thumb into his mouth and started to suckle on it as he kept destroying the seat of his pants. 
"I guess Draco's jealous of Ron's stink and wants to top it~ 'Isn't that right baby Draco?'" Harry asked.
Hermione was moving back to the other side of the table where the air was a little fresher but had to turn and watch in amusement as now only did the teary eyed blond nod his head up and down, helpless to refuse the command but he also lisped around his thumb making drool run down.
"Yesh 'arry. Ous wight." Draco whimpered and as he finished with the back of his pants, he closed his eyes and relaxed his bladder soaking the front. 
"Gah watch it!" Ron cried up, jumping up on the table before the smelly puddle the blond was making could reach him. 
Crab and Goyle had like wise stepped back away from Draco in part to avoid the puddle and the smell and to avoid being seen as besties with the pants pooping dork. 
Harry had been about to unleash his next command but instead decided to call off the torment for the moment as a certain raven haired potions master was storming towards Draco and did NOT look pleased. 
"Head's up stinky boy, your uncles coming." Harry advised and leaned back, casually munching on a slice of pie. 
'dinner and a show..never a dull moment at Hogwarts.' he thought. 
Sadly it wasn't much of a show as Snape just wordlessly took Draco by the ear and led him off, taking the time to turn around and use a spell to clean up the mess the blond had left behind.
"heh, I'd like to be a fly on the wall for that conversation." Ron mused. 
"Which the smell coming off of him flies wouldn't look out of place either." Hermione giggled, and that set them all off laughing. 

it wasn't till they were in the relative quiet of the dorm room (a glare from Snape had sent the few slytherin's who had been sitting in the common room scampering off) That Snape finally spoke up to the blushing and ashamed Draco.
"I thought you were done with this childish behavior after we had that talk during the summer young man." Snape said. 
"I..I wasn't doing it on purpose! Someone muse of cursed me or something!" Draco whined pathetically. 
this couldn't of been worse for the blond, his body just betraying him like that after that summer while Uncle Snape had been visiting he'd caught Draco purposely soiling himself and bouncing in it!
"Considering you've been with your friends all day and no one took out a wand in the dinning room, I think that's highly unlikely." Snape said dryly. "Do you remember what I told you before?"
Draco started to full on bawl and rub at his eyes, which combined with his soiled garments made him look like a over sized toddler. 
"T-That if you caught me messing m-myself like a little boy again y-you'd dress me to fit the role.." Draco sobbed. "Please! I'm telling you, it wasn't on purpose! give me anther chance!!"
"It's against my better judgement to do so..but I also don't wanna be the uncle of the only nappy lad waddling around the school. there will be NO more chances though young man, do I make myself clear?" Snape asked.
If Draco hadn't of already let all of his wee out in the dinning room, he would of soaked his pants here at the tone of his uncles voice and hiccuped and nodded.
"Oh for heavens sake.." Snape sighed and waved his wand, a oversized green soother popping into Draco's mouth and the poor lad found himself forced to suckle on it. 
he couldn't even seem to tug it out of his mouth and whimpered and pointed at it, looking at his Uncle.
"It'll come out once you get cleaned up. and after you're clean, strait to bed. no supper for pants pooper's." Snape said and then walked over, leaving the confused and ashamed boy the less then pleasant task of cleaning up. 
'I just know Potters behind this somehow..' Draco thought and due to the heavy load in his seat, he was forced to waddle to the bathroom to clean up. 
the only saving grace of everything was that Draco was so tiny downstairs his uncle had never been able to notice that despite how ashamed and humiliated he was, Draco was rock hard. 

word of Draco's accident spread like wild fire though the school and even though the teachers tried to encourage a forgive and forget policy Draco had simply made too many enemies in the school and was forced to endure multiple taunts, and worse, well meaning teachers calling him up to their desks several times a class and asking if he needed to use the rest room. 
the consent teasing had a effect of making Draco keep his fat mouth shut for a change and true to his earlier self promise Harry left him alone, though lord knows he longed to test the rumor he'd heard that Snape was prepared to put Draco back in nappies should he have anther accident.

At dinner that evening Harry noticed that Draco was sitting alone, other students had bunched in together as close as possible just to avoid being near him 'in case he went off' again. 
Feeling a tiny bit of guilt Harry, after clearing it with Ron and Hermione, got up to go and invite the poor git to sit with them. 
Draco was munching slowly on a piece of bread, resting his head on a fist and staring off with a million mile stare when Harry got his attention.
"Hey Draco, I wa-" Harry started but was cut off as Draco yelped and jumped, snapped out of his daze. 
this got more laughs from the other students and Draco fumed and blushed as he glared at harry.
"What do YOU want?" he huffed.
"I was wondering if you wanted to come over and sit with me and my friends..you look a little lonely." Harry said, forcing down the urge to make Draco disgrace himself.
the blond HAD had a rough day after all.
"Do you really think I've sunk THAT low I'll take your pity just like that potter?" Draco huffed and leaned forward. "I don't know how, but I know for a FACT that somehow you were behind what happened yesterday. So thank you, fuck you." and Draco tossed the rest of the bread in his hand at Harry's head. "BYE!"
eye twitching Harry clenched a fist and for a second thought of taking a swing at the brat, but again cooler heads prevailed because to be honest, Draco had EVERY right to be pissed with Harry and was on the nose. 
Still, he couldn't just let that go away totally unpunished and snorted.
"Fine whatever. 'Why don't you just sit her and sulk while you suck on your thumb!'" Harry said and turned to leave, knowing even without the laughter that started up that Draco had just started to nurse on his thumb like a pouty toddler. 
the thumb sucking command would only last for 5 minutes but it was enough to get even more laughter directed Draco's way and a look of disdain from Snape. by the time he was able to free his thumb for his needy mouth Draco would have a extra nick name to go with Potty pants Malfoy: Sucky baby Draco. 

with what happened in the dining room proving to Draco for sure that Harry had SOME form of a hold over him, he had planned to go over all the books and scrolls available in the common room to try and figure it out.
He was willing to pull a all nighter if that's what it took. However the other slytherin's had other plans. 
"oi, isn't it past little thumb suckers bed time? it's going on 7:30 after all." Crab asked, blocking his path to the book shelf and smirking.
"Bugger off, you know I can keep later hours." Draco said and and went to move around him. 
"you know.." Pansy said in her smug voice. "I heard that if widdle Draco her makes anther mess in his undies, it's back to nappies for the wholllle year~" 
Draco gulped and paled a little, noting how Goyle was coming up behind him now and back stepped away for his clearly ex thugs and friends. 
"I..I mean..G-guys c-come on.." Draco whimpered, realizing just how out classed he was in a physical fight have like a doofus having forgot his wand in his room. 
"So it IS true!" Pansy said and let out a shrill laugh.
"I think you should just get it over with BABY Draco. Snape's coming back any time now and can see you in all your smelly glory again." Crab chuckled.
"I..Uh..I don't even have to.." Draco mewed and held up his hands. 
"oh, you need help  disgracing yourself? All you had to do was ask." Goyle said and unleashed a powerful gut punch that sent spit flying out of Draco's mouth and sank him down to his knees holding his gut, looking up at a sneering Goyle who added. "what are friends for?"
the fear had been working his bladder like crazy and Draco had had maybe one too many drinks of milk at dinner because the force of the blow had his poor bladder unleash and for the second in for the second night in a row, he started to flood his pants.
"Hahahaha the baby is wetting himself!" Pansy laughed then turned to see Snape standing there. "Professor! you're just in time! Draco wet himself! are you gonna put him in nappies now?"
Draco was sniffling and tears welling up in his eyes as he turned to look at his uncle, who strolled over with a look of anger on his face and taking out his wand.
"U-Uncle Snape Please I-" Draco started, but then Goyle, Pansy and Crab suddenly turned upside down and were floating in the air,
"How utterly stupid do you three believe me to be to think that you could fool me like that?" Snape asked in a quiet voice full of rage. "even if I hadn't of been standing there and seen the last little bit of that, you really think I wouldn't of found the bruise?" he added and started to move his wand up and down shaking the three bullies and making them knock together before dropping them in a heap on the ground. 
"W-We're sorry!" Yelped Goyle, who was the first to scrabble to his feet.
"Won't happen again!" Crab added getting up.
"Totally hands off!" Pansy finished and got to her feet.
"Oh no, you'll be hands on. If ANYONE else threatens Draco with physical violence, or worse..carries it out, it'll be YOU three I blame and come after. so it's in your best interest to make he stays relatively safe. That said, a little verbal humiliation will do him good, but Hand.Off. Do I make myself clear or do you need anther demonstration?"
the three got the point and scrambled off and as Snape went to turn to Draco he got the soaked and smelly boy glomping his waist and whimpering out thanks, getting snot on him. 
"thank you thank you thank you!" 
'...I'm getting soft in my old age.' Snape thought dryly and ruffled the boys hair and then lead the way to the bathrooms to get him cleaned up.