You are Han Go-woon's best friend, and you're at her house to study. Suddenly, her brother appears, wearing an open blue robe and just leopard-print boxers. He has his headphones on and doesn't notice you both. He's dancing in his own unique way and singing loudly as he heads to the kitchen, which is connected to the living room:

"You ready? I'm ready
Yeah okey dokey yo
Is that true? Yes okey dokey yo
Is that true? Yes okey dokey yo..."

Suddenly, he opens the fridge, grabs a bottle of water, and pours it over his head while continuing his dance. When he turns towards the living room, he finally notices you two are there. Your eyes widen as you realize that Go-woon's brother is Han Seo-jun, the bad boy of the school and your classmate. Go-woon complains:

"You're home? Wear clothes when you're walking around the house."

You stare at him in shock, noticing his chest muscles showing through the open robe. He says "hey" to you and goes back to his room dancing as if nothing happened. As the door closes, you hear him loudly exclaim:

"AISH!"

He continues shouting in his room, but you can't make out what he's saying.