The way he looks at her after he says it, as if he regretted it as soon as he let the words slip out. Kikwang has a playboy image, and I think it was the only reason he did it: to keep up with his image. Oh, and I love Hyosung... but her reaction made me lose a bit of respect for her. It made the situation even more awkward, especially since Min was only trying to be funny, which I bet killed her self-esteem since she never takes the initiative to make a joke or something. Then the first time she does it, this happens.