The three Donatellos

There is one surefire way for Donatello to get rid of his brothers so he can have peace. Well, two, but that's not the point. The surefire way is to mention the words 'transdimensional portal stick'. He's STILL trying to figure out how that other version of him got it to work (especially when it was originally a flashlight), but he does know that pretending he does gets them to vanish almost instantly. It's funny actually, he has started making a game out of how much of the word 'transdimensional' he can say before they leave. His highest score is 'transdim'.
He tweaked a few things and the portal stick started glowing, 'causing him to jerk his hands back. Moments later, Don found himself staring at two other versions of himself. One was about two feet shorter, and one was DEFINITELY two feet taller. "Whoa... Where am I?" asked the smaller one. The taller one had whipped out a little gadget and was scanning practically everything with it.
"Prodigious! I'm in another dimension!"
"Um, hi," said our Don, who we shall now refer to as ADon. The tall one is TDon, and the other is SDon. Remember that now.
"You must be this dimension's version of me! It's a pleasure to meet you!"
"It's a pleasure to meet you too," said ADon. SDon seemingly noticed him then.
"Hi, why is there a bed in here?"
"Because I end up sleeping in here sometimes," said ADon. SDon gave him a strange look.
"Too much time in the workspace can NOT be healthy," he muttered.
"Too much play isn't good for you either," said TDon. The tall and short one glared at each other until ADon coughed into his fist.
"Ahem. I'm assuming you two know each other?"
"Unfortunately yes. He came to my dimension awhile ago, and I've been trying to get to other dimensions since then."
"He can't stand me," SDon informed ADon cheerfully. "He was actually trying to strangle me with a stethoscope when you called. Thanks for the save."
"Lazyshell," TDon muttered.
"Workoholic!" SDon hissed back.
"Quit it! How about we have a nice cup of coffee then I can give you a tour of this dimension's lair?"
"Coffee? Are you nuts? Hot chocolate is what we need!" said SDon.
"He's certifiably insane," said TDon.
"Do you have marshmallows? Where's the kitchen? GEEZ this place is huge!" TDon and ADon trailed after SDon, who, despite his questions, already seemed to know the answers.
"Unfortunately, brother, he does not share our work ethic," said TDon.
"I can tell. He seems like Mikey."
"He does ingest a lot of junk, but he doesn't read comics. Then again, he doesn't read anything useful either."
"Yes I do!" said SDon indignantly. "Being able to recite the full first two chapters of The Fellowship of the Ring actually saved my brothers' lives!"
"A complete lie I'm sure," muttered TDon. They sat down at the kitchen table as SDon put three mugs on it.
"Drink up!" he said cheerfully. "This is my SPECIAL kind of hot chocolate. It's got plenty of caffeine."

About five minutes later, WHY you shouldn't give geniuses large doses of caffeine and sugar was revealed. SDon was dragging ADon out of his lab, and TDon was laughing hysterically at anything and everything. "I'LL DIE IF YOU TAKE ME TOPSIDE!" ADon shrieked.
"YOU ARE COMING TO HAVE FUN!" SDon yelled.
"HAHAHAHAHA, HE'S GONNA DIE!" TDon laughed. Raph, Leo, and Mikey were hiding- err.... Observing- from the upper floor.
"He got the transdimensional portal stick to work, I guess," Leo said.
"And it made him insane," Mikey added.
"No, that's just you," said Raph. SDon dragged the other two Don's out of the lair, and peace settled.
"We are all going to act like that never happened," said Leo. Raph snorted.
"Speak for yourself Leo, I'm gonna go get more blackmail material."
"Me too." Leo sighed as they ended up following the three Bo-wielders.

"Where is it possible to have fun here?" asked SDon, who was incredibly serious right now.
"Hehehe, look at that old lady crossing the road," cackled TDon.
"Ignore him, he's an idiot," said SDon.
"Hehehe, idiot."
"Well if we HAVE to be up here, why not go to the Shredder's tower," said ADon, who was sulking.
"TO THE SHREDDER'S TOWER!" bellowed SDon.
"Hehehehe, Shredder is a shedder. Hehehehe." Why yes, TDon IS insane when he has sugar and coffee. How did you guess?

The poor Shredder was sleeping when a pair of green hands wrapped around him, and the freckled, giggling owner placed him in a new robot body and strapped him in, then put him and his new body back in bed. "Hehehehehe, I'm done." On cue, there was an explosion from downstairs.
"PREPARE TO HAVE FUN!" bellowed SDon. Foot ninjas yelled in confusion as bazookas were fired and it started to smell like maple syrup. "Level one of n00bs pwned!" SDon declared. "Prepare to move to level two!"
"I have the glue grenades ready," said ADon, handing some to SDon.
"Mah boi, you have done extremely well."

From a nearby rooftop, Leo, Raph, and Mikey watched incredulously as their brother and his two counterparts steadily sent Foot ninjas screaming out of windows. At one point, it looked like they were knocking their opponents out by hitting them with socks. "Those have to smell awful," remarked Mikey.
"Maybe they're yours then," said Raph. Mikey frowned.
"Maybe they're YOURS," he snapped. Raph snorted.
"I hardly ever wear socks, Mikey. Don't need to, remember?"
"BONZAAAAAAAI!" they heard, and looked up to see the second-to-last floor's windows blow out.
"HAHAHAHAHAHA! Peanut butter! HAHAHAHAHA!" They exchanged a look, then silently agreed they needed a closer look.

ADon and SDon were trying not to laugh, and TDon looked immensely pleased with himself. The Shredder, in a robotic chicken outfit that was JUST big enough for him, was outraged, and purple in the face. He couldn't go red, seeing as his skin colour was red. TDon guessed that the utrom had originally been pink, but had been angry so often that he changed colour. This made ADon and SDon lose their control and start laughing uncontrollably. And the Shredder screaming that he was going to kill them made it worse. Who in the world would take a pink chicken seriously? "Ready?" asked SDon, aiming a gun at the screaming alien, who's screams changed from rage to fear.
"Aim!" said ADon.
"FIRE! HAHAHAHAHAHA!" TDon pressed the button and the miniature tank they were sitting on covered the Shredder in his LEAST favourite substance. CARAMEL.
"Does anyone else now think the Shredder has raspberry filling?" asked SDon.
"Okay, party's over," said a voice, causing them to look up.
"Hothead! Hehehehehe."
"Will you shut him up?" asked Raph, giving TDon a sour look.
"Next to impossible," said SDon. "Now mah boi, what can I do for you?"
"You can get your green behind back to the lair so we can send you back. And tall'n'nerdy."
"Hehehehehe, nerdy! Hehehehehe!"
"But we are having fun! You shall not stop our mission!" said SDon, pushing Raph out the window.
"YOU SON OF A TENTACLED BASTARD!" shrieked Raph, barely managing to save himself.
"Hey! I'm right here!" snapped the Shredder.
"Good," snapped Raph in reply as he climbed back inside. "Look, we'd like ta get this bus outta crazy town and back to reality where things make us confused in a NORMAL way."
"Might we go to my reality, where you turtles don't exist in any form?"
"Shut up," Raph said, starting to get convinced that there was something in the caramel making the Shredder a little loopy. Little did he know that sugar is like drugs to utroms, and makes them start hallucinating.
"MOMMY?! How did you get here? DON'T HIT ME IN FRONT OF MY ENEMIES!" The Shredder scrambled out of the room, but no one had been paying attention to the poor dude. Well, except for Mikey, who was recording everything.
"Okay, we're gonna lock you in the spare room back at the lair until you've all calmed down, and then our Donny'll send you home."
"NEVADA!" TDon shouted, and jumped out the window, followed by SDon and ADon.
"ENGAGE YOUR PARACHUTES, MEN!" SDon bellowed.
"Why camera crews aren't out everywhere I do not know..." Leo said, as they took off after the purple-masked turtles.

Of course, all good things come to an end, and the three turtles had their sugar crashes after completely redecorating the Statue of Liberty (she was given an afro, side burns, a mustache, a hoodie, skinny jeans, and high heels). How they accomplished redecorating her is a mystery, which some poor clean up crew will have to get rid of. When the Dons woke up, SDon admitted (quite cheerfully) that everything was his fault. TDon was appalled with the night's activities, and ADon had resigned himself to teasing from Mikey.

After the other two Dons left, Donatello was given the lecture of his life by Master Splinter, involving how shameful it is to humiliate a fallen enemy, et cetera et cetera.

All Donatello knew was that he'd HAVE to do this again sometime. Perhaps with Leo...