How long do I have to wait before I can blow out of a boring dinner party?
You need to wait at least 40 minutes from when dessert is served, but less if it's exceptionally late, you've got six screaming children in tow or you're leaving on a promotional tour for Mr. And Mrs. Smith II early the next morning. Any sooner than that and your host can accuse you, fairly, of eating and running, though if they're as boring as they sound, that may be your goal. Better still, why not try and outbore them? Start random sentences with, "Remember that time on Battlestar Galactica...?" And don't forget to act offended when they show you the door.