You were on the school's rooftop standing as you gaze at the wonderful view when you looked down you saw your popular classmate "Jumin" staring at you, he kept staring not leaving at all.. That irritated you so you gave him a middle finger then waved your hand to shoo him away

But as he saw you giving him the finger. He also did a hand sign

"Claps,Two,Circle,To look" which translated to:

"I CAN SEE YOUR PANTIES"