"Julebord", which if translated directly means "Christmas table", is a fine Norwegian tradition. It's basically an extended dinner party, usually held in the month or so leading up to Christmas, and usually arranged either by a company for it's employees, or by a society for it's members. If it's just a party with a bunch of friends, it's not commonly called a "julebord".
The time from around the middle of November until Christmas is often known as the julebord season, and with good reason. Almost all companies with more than a handful of employees have a julebord, which means that unless you live far away from civilisation, at any given day odds are there are several julebord going on, which can have a quite noticeable effect on the nightlife of a town. For many grown ups, the julebord is the only time of the year when they can drink like they did when they were teenagers, and since it's so long since they were teenagers, they have forgotten it was a bad idea.
As a university employee, I have had the good fortune to be invited to two julebord, one held last week by the faculty of science and technology, and one next week, by the section for applied physics. For our French post.doc., this was his first encounter with this beautiful Norwegian tradition. As the julebord is such a big thing in Norway, we naturally felt we had to prepare our French friend, so we started weeks in advance, describing all the important things to remember during the julebord.
First of all, it is traditional to get very drunk. While I have never adhered strictly to this particular side of the julebord tradition, one must assume a lot of people do, as all the largest Norwegian online newspapers will usually run an article in early November, warning people not to get too drunk and pass out outside in the snow. In order to facilitate this, alcohol is usually served at a julebord. The selection depends on the food, but if Christmas food is served, there will usually be Christmas beer and aquavit. If you work for a really rich oil company or similar, the alcohol will probably be free. For the rest of us, there will usually be either the option of buying alcohol, or each person will get a certain number of vouchers for the bar, or a combination. Thus, in order to uphold the tradition of getting very drunk, it might be beneficial to bring something in a hip flask, or a "lommelerke" as it is known in Norwegian.
Drinking has traditionally been a thing connected to shame in Norway, and for this reason (and more importantly, because you might get thrown out of the venue) it is important not be seen while drinking from your lommelerke. The two most common ways to ensure this is either to pour the contents into a cup of coffee, or to head of to the bathroom to have a few sips. Our Frenchman complained that it sounded very sad to be hiding in the bathroom, drinking by yourself, but we explained that traditions are traditions, and that was that. Luckily, they only filled our coffee cups half full, which meant that we didn't have to sneak off to the bathroom, and also that we got a chance to explain the crucial difference between "coffee" and "just coffee".
Furthermore, it is important to be rude to your coworkers, or make love to them. Or both. Again, this is not a part of the tradition that I have participated in myself, but the newspapers warn against this as well, explaining that cheating on your spouse with a co worker can lead to awkward situations at home and at work, so I must assume it is quite common. Also, it is important to tell the boss how you feel about him/her, and how you are convinced that you could do a much better job yourself. While this is technically being rude to a coworker, it such an important part of the tradition that it deserves at bit more attention. For best effect, one should always stand on a table with a glass in one's hand when launching the tirade against the boss. You will know you have done this correctly when you show up to work on Monday to find you have been fired.
To finish the evening in style, make sure to start a fight in the taxi queue, get arrested or pass out in the snow.
Unfortunately I've never actually taken any pictures at a julebord, but google can give you the general idea: Google Images: julebord