For my current manuscript, I'm writing a story about a sixteen-year-old boy. I am having a hard time coming up with a motivation for a scene. I have one ready to go where the (not well-off) protag's best friend convinces him to go to a party at some rich kid's house. The events at the party are important to the rest of the story. (Not least because the protag will meet his Love Interest here.) These two guys have to go to this party.

My question is, WHY would they? They don't like these kids in particular. It isn't their crowd. They can get free alcohol elsewhere. So, why? I mean, sure, they could just be bored and hear about this deal and decide to show up for the hell of it. But I'd like the reason to be more important than that. I want them to have a goal in this scene. Something they want and are trying to get.

Anyone have any suggestions? (I have thought of a half-dozen or so, but none of them seem quite right.)