Some time ago, a southerner (a person from southern Norway that is), visited a small fishing village up north. To start with he had a hard time understanding the ways and humor of the people in the little town, but as the days passed on he got to know them better and better, and befriended them all. As the day came when he was to leave, they had a farewell party organized for him. And as the party drew to a close, one of the townspeople rose up to say the last words. At the end of his little speech, he said that "we have all concluded that you are in fact a really nice horsecock", and although the southerner himself was a bit puzzled by this remark, many of the townspeople were touched to tears about this unbelievable compliment.
This story is probably not a hundred percent true, but it nevertheless highlights some of the perceptions of northerners in our country - that is both their own self perception and the perception of others. Now, the fact that there is a divide in some ways between people in different regions in a country is nothing particular for Norway. You do have the same in France, in the UK, in the USA, and in Germany (think Ossies and Wessies), and problably any country in the world in fact. But what lies behind the differences (perceived and real) is quite interesting, I think.
According to the stereotype, the northerner is utterly straight forward. He is telling everything as it is, straight from the gut. Uncomplicated and unpretentious, he is free of any urbane streaks. And his language of course, is juicy and full of imaginative swearing. An independent soul, never giving up no matter how dark things (literally) look. And as for humor, it is at times dark, at times light hearted, but mostly very coarse and a lot of the time of a sexual nature.
I guess the development of the nature of the northerner (perceived or real) can be at least partly explained historically. (Note: the following is largely speculation and my interpretation of things. I do not have very much academical backing for my claims here.) The northern parts were (and some say it is still) quite provincial, being the back waters of Norway. In fact large parts of the borders were not drawn out until in the mid 18th century, at least in part reflecting the irrelevance of this area for the government in Copenhagen (as Norway was in union with Denmark at this time).
It is easy to imagine how people in this situation would develop a character different from the urban centers down south. This situation would have encouraged a mentality of self-reliance, as people would have to cope with their lives without any help from outside, and in short a "tougher" and coarser mentality than you would typically get in more urbane settings. And of course, as people sometimes tend to define themselves by their differences compared to others, this might have been a self-reinforcing process as well: "We are a tough bunch, much tougher than those sissies down south"
Even today, a lot of northerners are defining themselves based on the perceived differences from southerners. We up north have an image of the "typical" southerner as a wimp and office rat, sipping his caffé latte or whatever they drink down there, and we define ourselves pretty much as the antithesis to this. We take pride in being able to withstand the harsh and cold weather (never mind that there are regions further south which have much colder weather than us), that we have such a coarse and simple humor, etc.
I may be partly to this, but I must say that I agree with this conclusion. The dialects of Northern Norway has some sexy associations and connotations to it in many respects; it is something fresh and honest about it. Interestingly enough, the dialect that come out second in the survey was the far-south dialect; on the other extreme of our country. 
