Skip to 1:35 for the background story. And if you're super lazy, skip to 3:30 for the real juiciness of it. This is essentially a followup to my first post about girls shaking hands. Note how with Jimmy Kimmel (and this is usually how it works), Megan Fox shook his hand and then did the kiss on the cheek. The problem is the ambiguity of such a procedure because although at first glance you think she's going for the handshake, this sort of "code" has developed that all talk show hosts kiss female guests on the cheek, even if meeting them for the first time (and therefore initially shaking hands). Although Jimmy and she may be meeting for the first time, they are trying to make it appear as if they are well acquainted because it gives the audience the impression that they are friendly/friends which makes for a smoother and less awkward interview. I think this is why the kiss on the cheek convention came about for talk show hosts.
Too bad for Seth Rogen though, because this rejection is just brutal. In a way, it's almost better that it occurred on national television because at least then you can look back on it and laugh and perhaps even have a joke with Megan Fox about it. Had that occurred at some random cocktail party in front of two awkwardizers you barely know, you would probably just pretend like it never happened and even if you wanted to bring it up, barely anyone saw it and the girl would probably find you creepy for remembering it weeks later. Just look at Seth Rogen's face right after he gets rejected, he nods as if to act like he was expecting it the whole time and wasn't even going for it: he's desperately trying to play it cool, but in that situation, "playing it cool" is just damage control.