Comical. That's what the scene was. Hikaru and Kaoru quickly pulled apart, hands covering their mouths, a wide blush on each of their faces. Of course, all of their fangirls were squealing in delight, the rest of the host club were looking on with faces of pure shock… even Mori. Kaoru replayed the scene is his mind, and so did Hikaru. Both of them thought it would be fun to act as each other for the day, so far, not even Haruhi noticed. So that meant Kaoru was Hikaru in the HOST CLUB. Kaoru was the 'pitcher', so to speak. Kaoru obviously wasn't good at it, judging from what just happened.
*Flashback *
Kaoru (meaning Hikaru) had purposely tripped over a chair. Hikaru (meaning Kaoru) had rushed over to his brother's side.
"You need to be more careful, Kaoru." Kaoru had said, helping Hikaru to his feet.
"I know, Hikaru, but it's hard to pay attention to where I'm going when you walk right in front of me…"
Kaoru had pulled Hikaru's face up to his own meaning to say, "I feel the same way, Kaoru, but you don't have to advertise it. Now you've gone and made ME embarrassed this time." but instead, he had accidentally pulled his head up too sharp, too fast and their lips came together as if Kaoru had meant it to happen.
*End flashback *
And that was a day Renge, and other fangirls, would never forget.