As Americans, very little of our culture is taught to us in the traditional sense. What we tend to learn about our own society is what gets filtered to us through the lenses of cameras for either TV or movies. There really are no rights of passage for our culture other than general teenage mischief, usually fueled by lust and alcohol. This can work against you when you are a guest in another country, especially this time of year.
For example, if you are living in Saudi Arabia, and are not Muslim, for Godsakes DON'T go caroling! Just trust me on that one... And the old mistletoe scam to get the hot chick in the office to kiss you, could potentially lead to a public execution in that same area of the world. Here's a field guide of what to do and not do if you live in the Arab world.
If you live in Hong Kong, the big party isn't until the 27th when the Taoists celebrate with a festival called Ta Chiu. This is a pretty mellow ceremony where every person's name who lives in the area is read off of a list by the Taoist priests, and then that list is glued to a paper horse that is then set on fire. As interesting and exotic as it may sound, remember that this is Hong Kong, so that list of names is going to take a while; make sure you take a Snickers. And to avoid the torches and pitchforks, do NOT try and cook meat over the flaming horse as this is the mechanism in which the names are received by heaven. It would suck if someone ended up having a cruddy year because their name floated into your KC Masterpiece instead of the cosmos.
Predominately Buddhist Thailand celebrates Christmas as a way to close out the year with a nice festival. They use the same imagery and decorations, and the kids all have that same anticipation of Santa's visit. You expats in Thailand are pretty safe to let loose here as the only offense you could really give is when you get that white and red striped peppermint injected dead scorpion and scream instead of eating it like candy.
Expats in Norway who are invited to Christmas dinner by locals will be treated to the traditional dish called lutefisk. This is fish that has been treated with lye until it has become a jelly like caustic fish substance. Smile, choke it down, don't cry, and make no reference to the fact that this was probably the food that made the vikings so mean.
So there is a small sample of various Christmas traditions and how not to upset the locals in your host countries when celebrating. I hope this helps!!