too cool for the room
When someone acts like they're all that, usually kicking back and not participating in anything that's going on.
Yeah, he thought he was too cool for the room, but he really wasn't.
too cool for the room
Describes someone who states dislike of that which is popular or sucessful while supporting somehting more obscure in an attempt to appear "deep" or "in touch."
Jim doesn't like Aerosmith, he says that Stone Kotex is a much better rock band. He's just being too cool for the room.