[X] Go for the low blow
"She's not my girlfriend!" Sasuke says indignantly.
You snicker. "Do you really think
you're the best person to be giving Sakkun relationship advice? You can't even get a date hanging out with the Clan Heir."
Shisui staggers back as if struck. His mouth drops open, and his left eye starts twitching in disbelief. For a moment he's speechless; the only sounds he can make are little choking noises. Finally he manages to blurt out, "S-so cold..." And he retreats to a corner of woe.
Sasuke blinks in surprise. "You broke him."

"Couldn't have happened to a nicer guy."
"... are you sure you aren't some kind of Sharingan thief?" Sasuke asks suspiciously. "'Cause there is one in town; I heard dad talking about it with mom."
"Why would I want someone's eyes?" you ask, cocking an eyebrow. "I already have two perfectly good ones."
"Then do you have some sort of Byakugan offshoot?" he persists. "You don't have pupils, just like a Hyuuga."
"I have pupils!" you protest. "You just can't see them 'cause of stuff I can't talk about with people outside the clan. And no, no Byakugan."
His line of inquiry exhausted, Sasuke seems to be wondering what the hell he can say next.
"... wanna walk home together?" is what he finally decides on, for lack of anything better.
[X] "Sure." Lollypop or no, Sasuke seems like a nice enough kid.
[X] "Nah. It'll just make everyone in class decide we're boyfriend and girlfriend, like Shisui-baka did."
[X] "Sure! Ne, can we hold hands?" Sure, you're too young for boyfriends
now. But there's no reason you can't start laying the groundwork for future developments. ;D