[He's cool, and he's a senpai, therefore he's a cool senpai! Obviously!

Though the "cool" part might be debatable.

Especially right now. He's trying to keep the upper hand, trying to tease Jun and stroke his desires further. But he's rapidly losing his cool as Jun continues to explore, crooking a finger inside him and stroking, looking at him with heat in his eyes and asking him if he feels good, all gentle and attentive and eager to please. When that finger curls, it brushes a sensitive area, and he sucks in a breath, eyes fluttering. It's not an intense, immediate pleasure, but it's something. Isn't it? All he knows is he wants to feel more of it.

And, eventually, even more than "more."]

Maybe! ♪

[He singsongs back, but it sounds high and flustered. There's more heat on his cheeks now, and the feeling of Jun's length pressing against him makes his own cock throb. His hips squirm a little, pushing Jun's finger into him, hands holding onto the sheets tight. But he still finds it in himself to tease.]

Jun-kun's thinking it'll feel good when I'm squeezing another part... right? When he's got something else in me... ♪

[(This would probably be more effective dirty talk if he could actually say the word "dick.")]