I'm pretty sure they didn't do anything. He just probably sweating from dragging him. Also the mc was sober and they both hate each other.
Somehow they're in clothes, that's probably what it is. Starting that way would eradicate all the barbs that launched during those chapters. It would be from 0 to 100 very fast.
Though that might be the trigger for Kihoon to feel something for the MC.
Comment section is filled with second hand embarrassment. Me over here is used to feeling embarrassed so it's become a normal feeling