"Yes, sir." Shiro chokes on his drink, as soon as he's done hacking up a lung he shoots a glare at Keith.
"Don't you dare. We are the same rank and you know it." Shiro hisses. Earlier, he'd complained to Matt about the newest cadets saluting and calling him sir, despite the fact he hadn't made Officer yet. Apparently, Matt and Keith had been talking.
Keith's face is a perfect mask of cadet addressing a superior, "As I see it, sir," Keith's lips keep trying to quirk up into a shit eating grin as he speaks, "Being the tutor in this situation, puts you in a position of authority. That makes you deserving of all the respect due to that position, sir." He's going to strangle Matt. His friend knows exactly what he's done by pulling Keith into his teasing.
"Seriously, stop it. It's not funny." It's the exact opposite of funny. He already has enough trouble not popping a boner during these sessions, when Keith does cute things like biting his lip in concentration. He doesn't need the other cadet repeating lines from the start of some of his after dark fantasies too.
"I disagree…sir" Keith's actually smiling now, which is the only reason Shiro's pants still fit comfortably.
Still, this goes on long enough, and he's sure, he'll lose the ability to stand up without embarrassing himself, "You want to play it that way. Fine, drop and give me twenty cadet." See how long Keith was willing to keep this up now.
Keith's pout is far cuter than it has any right to be, "You're no fun." He grumps, turning back to his books.
Shiro is not smiling like a love struck idiot. Keith is not the most perfect person in the world, and he is going back to their completely friend based tutoring session now…
He is so doomed.