[Whoa, his teenage self turns down the advances of Roxanne's teenage self? That's really fuckin' weird to Bro, considering how much he wants to pork that. But that's beside the point, and he needs to focus on other things.]

Well you do know that the house is full of mistletoe, don't you? Of course you do, considering you ambushed me under one. I think it's safe to assume something similar happened with them. It seems to me that Dirk's got a thing for the guy, so it's entirely possible that Dirk set it up so that Jake had no choice but to kiss him.