A/N: I kinda got dared into this one by Teebs in a very roundabout way via Tumblr. I did say quite clearly at the start that these things are all just headcanons, and so therefore some are far more ridiculous than others. This is one of them. Jeff Tracy meets the Teenage Mutant Ninja Turtles. Yes that's right, I went there. I totally did. Don't even pretend that this isn't a crossover you've all secretly wanted your entire lives... (okay fine, maybe it's just me, then)

Disclaimer: Teenage Mutant Ninja Turtles were originally created by Kevin Eastman and Peter Laird and are now owned by Nickelodeon. Title is taken from "Shell Shocked", the theme to the 2014 TMNT film, by Juicy J, Wiz Khalifa, Ty Dolla $ign, Kill The Noise and Madsonik. No, I'd never heard of them either.

Also, my apologies to any Japanese readers who note my (terrible) translation of a particular line in this story. I used Google Translate in the absence of actually knowing any Japanese people I could ask. Sorry.

3. You're About To Get Shell Shocked

"Why did you bring him here?"

"Bro, look at him! Maybe he's a wizard!"

"I don't think he's a wizard, Mikey."

"He's like a hundred years old! He's got all this grey hair! He has to be a wizard!"

"Not necessarily, uh, if you take someone like Harry Potter, for example, he was a wizard but he was -"

"I don't think you're helping, Donnie."

"Maybe he'll magic us up a sixty-two cheese pizza?"

"C'mon, Mikey, that's just a legend, those things don't really exist!"

"WIZARDS CAN MAKE 'EM!"

"We gotta get this dude outta here before Sensei sees him and-"

"Before Sensei sees who, Leonardo?"

Four green heads tilted sharply upwards before one slowly turned around.

"Funny story, Sensei," Leonardo said, giggling awkwardly as he began his frantic search for an appropriate way to explain his current predicament.

"It wasn't funny at all, some dude fell outta the sky and landed on Mikey's head," Raphael chipped in.

"Where the hell am I?" a voice behind him asked in a low, groggy tone.

"The wizard's waking up!" Michaelangelo said in a hushed, reverent tone before rushing over to the dazed figure on the couch. "Your Wizardness... umm... Your Magicalness! How did you come to this realm, dude? You lost, man?" he asked.

Jeff Tracy blinked four times as he looked at Michaelangelo, but he didn't reply.

"Maybe he doesn't speak English!" Michaelangelo thought aloud. "Donnie! Have you got your translator machine? Maybe he's Canadian!"

"Mikey, he's already spoken in English! Besides, Canadians speak English too!" Donatello answered wearily, walking over to his younger brother. "Sir? Sir, can you hear me?" he asked.

Jeff continued blinking intermittently. He had no idea what to say. One minute the pilot announced he was losing control of the plane, the next, he was... where the hell was he? What the hell was happening?

He sniffed the air and his expression crumpled in disgust.

"It smells like sh-"

"You're in the sewers, sir," Donnie said, quickly interrupting him. Mikey still didn't know that the smell in the sewers was attributable to human waste and the very idea of it would have sent him into a state of apoplexy.

"What am I doing here?" he asked. He had more pressing questions, of course, like why he was having a conversation with a large talking... what even was that thing? A frog? A terrapin?

"Raph found you, Your Royal Enchanter!" Mikey said, not even daring to look Jeff in the eye. Jeff frowned.

"I only found him because he'd LANDED ON YOUR HEAD, doofus!" Raph answered, grumpily.

"I'm... I'm not a wizard, son," Jeff said, cautiously.

"You're not?" Mikey asked.

"No, I'm just a regular guy," Jeff said. Michaelangelo heaved a loud sigh of relief.

"All right! It's okay, guys, he's just a regular dude like us!" he called to his brothers. Jeff's eyes widened.

"I'm not... I'm not quite as regular as you," he said, sitting up cautiously. "I mean, I don't... have my own bandana, for one thing..."

Mikey tilted his head to one side and looked up at Jeff with his huge baby blue eyes that would quite probably have melted the heart of a rock. Jeff looked back at him and felt the strangest wave of paternal emotion wash over him. Without another word, Mikey untied his bandana and placed it carefully in Jeff's hands. Jeff looked from the bandana to Mikey's freckled face and back again.

"Thank you," Jeff said, genuinely touched by the kind gesture.

"No problemo, old dude. If you feel like you don't fit in, it can stop people seeing how awesome you really are!" Michaelangelo said, squeezing Jeff's arm affectionately. Jeff blinked twice. He was approximately ninety-eight percent sure he was having a bizarre dream.

"My name's Jeff," he said.

"I'm Michaelangelo. These are my brothers, Raphael, Leonardo and Donatello," Mikey said, pointing to his brothers in turn before gesturing towards a large purple-robed rat behind them. "This is Master Splinter. He's our sensei and our Dad. He's old like you," he said.

"Michaelangelo!" Splinter said, sharply. Mikey blushed and Jeff couldn't help but smile. He had absolutely no idea what was going on. Everything seemed real enough, but his brain still refused to allow him to believe what was right in front of his eyes.

"I don't think I'm awake... but it's nice to meet you all, anyway."

"I know we look strange to you, Jeff. But I can assure you, you are in no danger here," Splinter said in a gentle voice. "Is there anything we can get for you?"

"I guess a stiff drink's outta the question?" Jeff asked. The turtles frowned but Splinter grinned and let out a breath of laughter.

"Leave it to me, Jeff. Mikey's gonna rustle you up a stiff milkshake like you never even SEEN before!" Mikey said, cheerfully. "So much ice-cream in it you can stick a spoon in there and it'll stay up!" Jeff laughed indulgently. That absolutely was not what he meant, but he didn't care. The easy humour and sunshine soul of the little turtle was infectious. In a strange way, he reminded Jeff a little of Gordon.

"Thanks, Mikey," he said. "How long have you lived here?" he asked, turning to Splinter.

"Fifteen years," Splinter said.

"I bet you've got a helluva backstory!" Jeff commented. Splinter nodded.

"You could say that. How about you, my friend?"

"I guess you could say that, too," Jeff answered with a grin. "These are your boys?" he asked, gesturing to the other turtles. Splinter nodded.

"They're adopted," he said. "Which explains why they don't look like me," he added, a mischievous gleam in his eye as he chuckled. Jeff smiled.

"I have five boys. A little older than yours."

"Where are they?"

"Home. I hope!" Jeff answered. "We, uh... we kind of run a business together."

"You must be a very important family," Splinter said. Jeff burst out laughing and shook his head.

"God, no! It's my boys. They do the hard work out front. I just sit here at the back trying to keep them in check!" he said. Splinter nodded.

"That is a feeling I can easily relate to," Splinter said. "I trained the turtles in ninjitsu, as my father trained me."

"Turtles who are ninjas?" Jeff exclaimed, his eyes widening. "Well! If that don't beat all! Do you have a use for nijitsu in the sewers?" he asked.

"You'd be surprised how often it comes in handy in New York," Leo said, mysteriously. Jeff shook his head.

"I wouldn't!"

"Here it is!" Mikey declared, walking in with the largest milkshake Jeff had ever seen.

"Heavens to Betsy!" Jeff exclaimed, not sure that he had ever used that phrase before in his life and quite sure he'd never use it again unless he saw a larger milkshake, which he wasn't sure was actually possible.

"I know, right!" Mikey said, his grin almost overtaking his entire face. "There's vanilla, chocolate, cookie dough, cream, jellybeans, anchovies, two types of sausage, topped with worms, algae and a morello cherry. Awww. Yeaaahhh!" he announced, closing his eyes and waggling his head with smug pride.

Jeff felt sick. He looked up at Splinter in a silent plea for help. Splinter was already ahead of Jeff in his mindset. His kind, warm-hearted youngest son was sometimes just not quite human enough for the outside world. Especially when it came to deciding what was and wasn't edible.

"Mikey, my son, your generosity is one of your greatest strengths. However, our guest has had a very strong shock to the system. Perhaps your milkshake will prove to be a little rich for his human constitution," Splinter suggested. Jeff sighed with relief. Mikey looked momentarily crestfallen before his eyes lit up as he realised it meant that there was more milkshake for him.

"No problemo, Jeff. I'll have it for ya!" he offered. His three brothers all exclaimed in protest.

"Tell him, Leo, he's gotta share that!"

"Raph's right, there's too much for one, Mikey."

"I've got some spare beakers in my lab, we could share it out in those!"

"Perhaps you'd like a slightly less protein-rich drink, Jeff?" Splinter asked. Jeff nodded. "Follow me," he said. Jeff cautiously stood up and wobbled for a moment.

"Here, let me help," Leonardo said, grabbing Jeff's arm to steady him. Jeff patted Leo gently on the shell.

"Thanks, son."

He followed Splinter into the dojo and obeyed Splinter's instruction to kneel at the table in the corner. After a few moments of hearing cupboards opening and closing, liquid pouring into cups, and the sound of paws and robes shuffling and rustling, a small cup of transluscent white liquid was set before him. He frowned suspiciously before looking up at Splinter. Splinter closed his eyes and nodded his head once before speaking.

"Sake."

"Sake?!" Jeff repeated, incredulously. Splinter grinned at him.

"I was not always the rat you see before you. Many years ago, I, too, was a human," he explained. Jeff blinked, now completely convinced that he was dreaming. "I have lived through hard times. I understand that water may be the source of life, but man has other needs too."

Splinter kneeled down at the other side of the table from Jeff, picked up the cup of sake before him with his front paws, and raised it in front of him.

"Kore ha anata no jido-ka sareta me no naka no doro desu!" he said. Jeff frowned.

"What does that mean?" he asked.

"It is a relatively new Japanese expression that roughly translates as, 'here's mud in your automated eye'," Splinter explained. Jeff laughed loudly.

"I think you and I are going to be great friends, Splinter!" he said, raising his cup aloft before knocking it back in one gulp.