Warning, Kalles Kaviar actually contains sugar and lots of it. It's horrible, and I'm swedish. They actually make ads on the TV with people from other cultures trying to eat it. It's not as bad as surströmming but ew...
To be fair, though: My spouse, the resident Norwegian, really likes it. Soetimes with a sliced, hard-boiled egg. But he's also been eating it since he was a child as it is a cheap and easy thing to make children. It is more akin to American children with peanut butter.
I, however, being the import to Norway, find it fairly disgusting.