Naruto didn't know what Sai was doing.
It was traumatising.
It made him shifty and uncomfortable.
And he couldn't look away. Because it also happened to be very...he wasn't sure what to call it. He cleared his throat a few times but Sai's mouth was still on the banana, and he was almost swallowing whole. He coughed this time, loudly, but Sai only glanced at him before going back to his banana and licking it.
"Um."
Still no reaction.
"Sai, what are you doing." He had to stop staring. He probably looked like a moron. Sakura would probably call him a pervert and punch him.
"SAI," he nearly yelled this time, and the other boy finally took his mouth off of the thing and Naruto felt like everything was right with the world again.
"What are you doing?" He repeated. He wasn't sure he wanted to know, but there had to be some kind of explanation. Please.
"I'm eating a banana."
"...I know, I mean. Why are you...eating it...like that," Naruto almost squeaked, trying not to flail. He wasn't 12 anymore, and he was used to Sai, so there was no need for embarassment. But it was still there.
"Oh, I saw it a in a movie!" Sai smiled his typical smile, and Naruto wanted to hit his forehead against the wall.
"I even picked a banana that was just about the size of your pe --" He didn't finish his sentence, because Naruto had launched himself at him and punched him square in the jaw. Naruto was uncomfortable about how much he'd enjoyed the wrestling that ensued for days afterwards.