Disclaimer: I don't own the manga/anime Naruto and I make no money in writing this…so please don't sue.

Notes: AU, one-shot, post-Kakashi Gaiden, pre-Naruto—Naruto is five years old or thereabouts. Not really related to anything else I've written so far. Read, review, and enjoy!

Edit (12/20/14): Now a two-shot!

Part I

Etymology: The study of the history of words, their origins, and how their form and meaning have changed over time.

"Say that word again and I'll wash out your mouth with soap!"

One of the most important lessons that Naruto had learned so far in his short, young life was that his mother's threats of punishment weren't empty. When she said that she'd spank him if he sprayed her flowerbeds with the weed killer that killed anything green, she would spank him. When she promised to ground him if he lied about stealing the cookies, she would ground him. And when she informed him that his mouth would be washed out with soap if he repeated any naughty words, she would wash his mouth out with soap.

But it wasn't fair!

Adults said naughty words all the time without having to worry about gargling soap. It was a sign of adult-ness to say the restricted words. And it was a sign of baby-ness to be forbidden uttering those special words. Naruto wasn't a baby—he was going to be a ninja!

Swearing was important to ninjas. It enhanced their toughness and meanness in addition to declaring their adult status. Even the youngest ninja swore all the time without reprimand. Stringing together the dirty words was practically an art among ninja! The amazing things that Naruto heard when he snuck around the fringes of the training fields set his imagination on fire.

He ached to practice this vital skill…but soap tasted nasty and gross, so he didn't dare.

But then Kiba let him in on a super-secret loophole.

If he took a naughty word and changed it just a little tiny bit into something not-naughty, he could say them all he wanted without consequences!

"Damn" became "darn". "Shit" became "shoot". "Crap" became "crud".

Naruto, Sasuke, and Kiba had been seriously debating the proper adjustment of a very naughty word that started with the letter "F" one day when Sasuke's older brother, Itachi, had stumbled across them. The much older and wiser boy had sternly warned them to not even try to modify the word in question. If the mothers ever figured out what they meant when they said "frick" or "fudge" or "freak" they would get punished anyway.

And so the largest and most colorful set of swears was lost to them until everyone else decided they were grown-up enough to not be subject to a soapy punishment.

It was horribly disappointing, but Naruto didn't let it bother him for very long. He resolved to uncover a naughty word that he could secretly use that was unique. He dreamed of a word or a phrase that would be all his own, and secretly filthy.

After much thought, he felt that he had uncovered the perfect word. It was something that his mother said sometimes when she was angry or excited or both. Whenever she was caught saying it, she would get embarrassed, like all adults got when they accidentally let one of the forbidden words slip in front of a kid. No one else seemed to say it, or even to know it…so it was absolutely perfect.

A week of secret experimentation led him to the modification that would make it safe to say in front of his mother and other adults.

The first time he tried it, his mother jumped and stared at him, but she gave him no warning. The next time he uttered it, Kakashi-nii-san stared at him, snorted like it was sort of funny, and went back to the paper-covered book that he wasn't supposed to read around Naruto. And the third time he tried it, just to be safe, his father had looked at him oddly before smiling, patting his head, and sending him off to play.

So Naruto made his special secretly-naughty word a part of his everyday speech. It became a place-filler when his mouth stumbled to spit out words fast enough. It expressed his anger, his excitement, his approval, his disapproval, his any-strong-emotion. It punctuated his sentences better than any exclamation point.

But then, one day, his father asked where that word had come from.

His dad—the second most super-awesome Hokage ever, because Naruto was going to be even better than him one day!—had been sitting at his huge desk, sorting countless stupid papers that were somehow too important to doodle on or practice origami with. Naruto had been sitting in a corner coloring in a coloring book because he was grounded from the playground for breaking a couple of things, and if he didn't stay here he'd have to go run errands with his mom. Frustrated that his picture wasn't turning out like he'd imagined and then by two crayons breaking in a row, he'd used his word, and then his dad had asked about it.

Reluctantly, and very carefully, Naruto explained it.

His male parental unit stared at him. Then his mouth twitched. Then he grinned. Then he chuckled. Then he laughed. Then he tried to stop laughing but he couldn't so he slapped his desk, clutched his stomach, and laughed harder.

"What's so funny?" his mother asked, stealing his question as she strode into the Hokage's office with a few small shopping bags from different stores hanging from her hands.

His father stopped laughing, stared at his mother, and then started laughing all over again.

"What?" his mother demanded, brushing a loose strand of super-long red hair behind one ear.

His dad tried to answer, but he was laughing so hard he was having trouble breathing.

"Naruto," she dropped her dark purplish-blue eyes down to him, "do you know what he's laughing about?"

"No," the whiskered boy answered with complete honesty. "I have no idea what I said that made him laugh."

She raised an eyebrow. "And what did you say?"

Naruto hesitated and fiddled with his broken orange crayon, but then his mom got the look on her face that meant that if he didn't answer quick she'd get mad…so he repeated his explanation.

"What word was your father asking about?" she asked with a hint of menace, like she was thinking it was that F-word that couldn't even be hinted at.

"Dattebayo!" Naruto exclaimed hurriedly.

His female parental unit stared at him. Then her brow furrowed. Then she frowned. Then she sighed and pinched the bridge of her nose like her head hurt. Then she reached into one of her shopping bags, pulled out a new sandal, and threw it at his dad's head.

His normally calm and quiet father was laughing so hard it sounded like he was crying and when the sandal hit him he slipped out of his swivel chair and slumped to the floor where he wheezed for breath between even more laughs.

"Mom," Naruto tugged anxiously at her sleeve. "I still don't get it. What's so funny?"

Being left out of a super-funny joke was a lot more awful and unfair than being forbidden to use naughty words.

"Let's go home so your father can collect himself," she sniffed, motioning for him to grab his coloring book and crayon box. "I'll explain as we walk, okay?" She shook her head and readjusted his shopping bags and muttered to herself in dismay. "He really is my son, dattebane…"