Author's Note: Felt the need for outright crack.
Tobi Reveal I
"No more escaping!" Naruto roared, hauling back. As he smashed the Rasengan into the masked man's face, he screamed, "WHO ARE YOU?!"
There was a sound like a watermelon exploding, and the headless body slumped down at his feet. He stared down at it. Then he turned back to Kakashi, scratching the back of his neck. "Uh... oops?"
"Well... some things just aren't meant to be learned, I suppose," Kakashi said, after several seconds of watching the body in case it tried to get up again. "Nothing to be done about it." He heaved a great sigh. "All we can do is be glad it's over..."
Tobi Reveal II
"No more escaping!" Naruto roared, hauling back. As he smashed the Rasengan into the masked man's face, he screamed, "WHO ARE YOU?!"
The mask shattered to reveal...
"OH, BULLSHIT!" Naruto screamed as the pieces dropped away, revealing another mask. Tobi gave him the finger.
"Welcome to the wonders of space-time jutsu!" the masked man chirped. "Would you like to try again? I've only got a few hundred more!"
Tobi Reveal III
"No more escaping!" Naruto roared, hauling back. As he smashed the Rasengan into the masked man's face, he screamed, "WHO ARE YOU?!"
The mask shattered to reveal...
"ART OF THE NINJA CENTERFOLD!"
As the smoke cleared, the newfound busty brunette stuck her tongue out at Naruto. "Eeh, Naruto-kun, didn't you realize the Sharingan can copy any technique?"
"You plagiarizing bastard!" Naruto yelled, pointing a finger at him. "Come over here and fight me like a man! Woman! Whatever!"
"So much for finding out his identity..." Kakashi murmured, squinting at the transformed "Tobi" and trying to work out what Obito would look like as a hot chick. Was it wrong to be attracted to your dead teenage teammate? And did he want to be right?
Tobi Reveal IV
"No more escaping!" Naruto roared, hauling back. Screaming "WHO ARE YOU?!", he smashed the Rasengan into -
A log?
As the wood exploded into a thousand burning splinters, he glimpsed Tobi standing twenty feet away, arms outstretched to heaven.
"PRAISE BE TO THE LOG!"
Tobi Reveal V
"No more escaping!" Naruto roared, hauling back. As he smashed the Rasengan into the masked man's face, he screamed, "WHO ARE YOU?!"
The mask shattered to reveal...
"Uh..." Naruto said, staring into the face of a pug-ugly guy who had some gnarly scars on one side. "Should I... know you?"
The man glared at him as he recovered from the blow. "Ask your teacher," he sneered. "He'll know."
"Actually, I don't," said Kakashi. The man gawped, then jabbed a finger at him.
"Enough fooling around! You know who I am!"
"I... really don't," Kakashi said, leaning on Gai as he scrutinized the man. "You're a short-haired Uchiha with odd scars. Since the Uchiha were fairly insular, similar features could turn up on several different people. That's even assuming it's your real face - Orochimaru had the art of stealing faces from others, but that didn't mean he was the only user. For all I know, this might not even be 'your' real body - you're a Rinnegan user, after all. Or it could be a creative henge. Anyway, supposing that is your real face, you may appear to be around my age, but that means nothing - you could be using a rejuvenation technique. Look at the Sannin Tsunade. Though you strongly resemble my old teammate Obito -"
"You don't say?!"
"- you might be his great-granduncle, for all I know," Kakashi continued. "Or you could be someone who's surgically altered your face to look like Obito as a demoralization technique."
"Don't think you're that important!"
"Not for me," Kakashi said, waving a hand, "but for when you - as Naruto informed me - attacked Konoha. Being able to whip off your mask and claim to be Obito might have taken the Fourth off-guard for a critical instant, enough for a skilled shinobi to score the kill. After that, you went around behind a mask anyway, so you'd have no particular need to change your face back-"
"This is such garbage, Kakashi, you know it's me," Tobi complained, throwing up his hands. "Admit it already so we can get on with it."
"As I've told you - no, I don't. And shouting at me won't make me believe it."
"Damn it!" Tobi kicked the shards of his mask aside. "What was the point of wearing a mask if you weren't even going to believe my big dramatic reveal?! All those years of buildup - ruined! Why even be a shinobi if your stupid teammate just blows off your show-stopping totally-unexpected maverick-ninja scene?!" He pointed at Naruto. "You feel me, brother?!"
"I feel you, brother!" Naruto shouted back, before freaking out at agreeing with the Akatsuki mastermind. "Wait, what am I saying?! I'd never agree with you! Whoever you're supposed to be!"
Kakashi's eye twitched. "For a moment there, I could almost believe that was Obito..."
Tobi Reveal VI
"No more escaping!" Naruto roared, hauling back. As he smashed the Rasengan into the masked man's face, he screamed, "WHO ARE YOU?!"
The mask shattered to reveal...
"I owe you 500 yen, Gai," Kakashi said with a deep sigh. "I thought it was far too obvious."
"Wh-what?!" Obito stammered, pointing a finger at him. "You - hey, what?! When did you have time to make a bet?"
"Oh, I've suspected since I first laid eyes on your ugly mug," Kakashi said, sounding bored and tired. "The mask, I mean. Let's see - you only had a Sharingan on the side I didn't take, you acted just as dumb as you ever did -"
"H-hey, take that back!"
"- and when you did get serious, you did it in the ultra-serious 'badass' way I'd expect out of someone whose development stopped around thirteen. If that. Obito, you haven't even changed your haircut since you were at the academy."
"You liar! I grew it out when I was going through an angsty teenage phase!"
"Mm. I'd need photographic evidence." Kakashi yawned. "As if that wasn't enough, your alias was To-bi. Very original, O-bi-to. If I tried to pass off 'Shika' as an original alias, ANBU would have disavowed me out of sheer embarrassment before the day was out." Running a hand through his hair, he added, "In fact, it was so embarrassingly obvious that I could only come to the conclusion that you were desperately trying to hide your real identity by obsessively imitating a random deceased Konoha chuunin. I had to admit, it was very effective. If I just assumed you had the brains of a radish, it was so obvious you were really Obito..."
"Er..." Tobi murmured, scratching the back of his head, and then jabbed a finger at Kakashi. "Well, I definitely fooled you! Because I really am Madara Uchiha! Totally! I - uh - took this eye off of Obito's corpse, yeah! And I'll prove it to you by kicking your ass!"
"What a shocking revelation!" cried Gai. "Kakashi, my rival, you can have back the 500 yen! Only through the power of teamwork and youth can we prevail against such a foe!"
Kakashi facepalmed.
Tobi Reveal VII
"No more escaping!" Naruto roared, hauling back. As he smashed the Rasengan into the masked man's face, he screamed, "WHO ARE YOU?!"
The mask shattered to reveal...
"OBITO!"
"KAKASHI!" Tobi screamed back.
"OBITOOOO!" Kakashi yelled, pointing a finger at the formerly-masked man.
"KAKASHIIIII!" Tobi roared, veins bulging from his neck.
"OBITOOOOO!" Kakashi wailed, his Sharingan weeping blood.
"KAKASHIIIIIII!" Tobi bellowed, his own Sharingan spurting blood in turn.
"Er... what's going on?" Naruto asked Gai, who was weeping regular tears of saltwater.
"This is the most sacred and manly bond between a man and his rival," Gai said solemnly, water streaming down his cheeks, oblivious to Kakashi shouting in his ear. "The crying of names... And my rival has abandoned me for his old teenage flame." He sobbed and wiped at his eyes with his sleeve. "After all these years of fidelity... he leaves me for some Uchiha hussy..."
"That's... all right, that's just weird," Naruto said under his breath, backing away from the manly screeching of names. "I'm just going to leave you two to catch up-"
Just then, Sasuke arrived on the scene, his face screwing up in a scowl as only an Uchiha's could. "NARUUUUUTOOOO!"
"SASUUUKEEEEE!"