Xiumin would probably try and keep a poker face, and gently lower his hands, but then end up laughing at how awkward that was.
Luhan and Kris would probably stop, with his hands still on your chest, then lower his hands after a brief moment. They’d awkwardly say, “Well… so… that was… nic— interesting,” before laughing hysterically.
Chen would drop his hands immediately, then proceed to exclaim, “Woah there! Tell your chest to get off my hands!”
Lay and Tao would apologize profusely and would probably avoid eye contact for the next three days.