This one is R-rated. :D
Naruto is on his first solo mission. Messenger. They wouldn't let him go alone if Jiraiya hadn't given his go-ahead -- Akatsuki is apparently having some sort of internal conflict; too busy to ambush him -- and if Sasuke and Kakashi weren't both out of commission. They double-KOed each other with the sharingan or something. He didn't ask, he was too busy laughing. Kakashi-sensei is still miles ahead of them all and he has his pretty sharingan, but they always forget that Sasuke's got two of them, and he can be really vicious when cornered.
Sakura's at the hospital, training under Shizune-neechan. And he really, really shouldn't word it that way. The mental picture is niiiice. Shizune-neechan is kind of plain, and she doesn't dress sexy at all, but when you look closer, she's kind of cute... Not as cute as Sakura-chan, of course. But still cute.
It's when he notices that he's adding the old hag Tsunade to his sweaty pile of pretties, and yet DOESN'T take his hand out of his pants, that he realizes something's a bit weird with him. But -- fuck. He doesn't care that she's long past the breeding age. He can just imagine her ordering her two pretty subordinates around -- though Shizune can be surprisingly bossy with Tsunade... would they fight for the right to initiate Sakura-chan? Would they team up? Would they scratch each other with their long nails and play with each other's hair, each other's breasts?
He could get jumped by the whole Akatsuki group and it wouldn't be enough to get him to stop jerking off. That's just the hottest thing he's ever imagined.
He's a hour late to hand the message over. It's hard to run fast when your legs are still shaking and your dick whimpers a protest every time it brushes against cloth.
On the way back to Konoha, he starts daydreaming about a mudfight between Ino and Sakura.