I had heard a fox yip long before that song came around. So it was a little frustrating during that brief period when trying to figure out if the song was a joke or not. It's hard to tell with Europeans sometimes.
If my sources are to be believed (and I have good music industry sources), the band was created just as an excuse to make some videos for a friend who had started a video production company. The Norweigan term for Fox is a slang word for marijuana so they had fun with that and they really liked that it sounded like an English curse word when sung with a hard X. The song is a joke on many levels and I think the biggest one is the fact that they have made a crap load of $$$ off of it.
We have no Carls here.
For all us East Coast folks, Carl's = Hardee's. Same ownership group, same basic menu.
If you want a seriously good burger, come to Baltimore and visit Alewife. I cannot personally attest to it (as I haven't had red meat in 25 years), but my wife is a burger fanatic and swears by it and it has won quite a few awards. It doesn't hurt that they serve it with duckfat fries and the beer list is amazing there.