Regarding Mona Charen's comments about being shocked to discover that Christians, instead of being home praying on Christmas Eve, were actually outside of their houses... it's been like that as long as I can remember. Sure, traditions vary, and some people do the big family dinner thing on Christmas Eve instead of on Christmas Day, but Christmas Eve has long been a "party the night before the holiday" for those inclined to do such things. And if you are going to cook a big meal the next day, you might just want to go out for dinner the night before.
And as for Christmas itself...Well, open presents, early meal, and then... it's movie time! Gotta do something before you start fighting with the in-laws.
I've spent a couple Xmases in England, where it's (hard to believe) a bigger deal than in the US. They shut down the tube/bus network in London so mostly people don't go out. But they do open the champagne at around 10 AM as it's perhaps the biggest piss-up of the year. Holidays are supposed to be fun!
As Roy says, why don't you know what your friends do for the holidays? Strange people.