From dinner today: "Be careful with the menu; you might order Buchanan by mistake."
I've identified the feeling: it's the feeling of the late afternoon of a snow day. Everything's on hold, and you don't yet know whether the next day will be a snow day, too. There's that dread in the air, there may be school tomorrow, the return to the unpleasant side of reality can't be postponed forever. Just a hushed waiting, and a feeling that what's going on isn't entirely real, and a lot of joking and jostling with your friends because you don't know what else to do when this sort of interruption springs out at you.