Person A is dared to kiss person B for five minutes straight, unaware. A complies and grabs an unsuspecting B, slamming their lips together. Let's just say they kiss for more than five minutes.

Not necessarily descending into smut.
Party? Was it a drinking game?
At school?
Frat party?
Truth or dare game?

I think MunchingUniverse is best for this, the cute but feisty, slightly nerdy Tyler, getting blown away by a smouldering hot kiss from jock/badboy/hunk Jason ;)