Why? Because he'll pee all over the place. That's why.
In Sweden, they make fun of Norwegians. One popular bumper sticker, for instance, reads: "Help third-world countries. Buy Norwegian cod." (In Denmark, in a similar vein, they make fun of Swedes, but that's another story.) The point being, as far as Swedes are concerned, Norwegians are not too smart.
In an effort to reinforce stereotypes, a 29-year-old Norwegian, who had evidently had quite the pre-party session before boarding his flight for Cyprus on Saturday, urinated in the airplane's aisle, sat down in a flight attendant's seat, and sparked a brawl sufficient to force an unscheduled landing in Denmark. He was led off the plane in Copenhagen, where he promptly got into a fight with the cops.
This is not to suggest that all drunken Norwegians are airplane aisle urinators, or even that you should avoid a drunken Norwegian when coming across one, say, at the Space Needle or the Underground Tour. That would be silly. Rather, let's celebrate the fact that we channel our Scandophilism into owning automobiles manufactured in 1980s Sweden rather than, say, getting drunk enough to ingest this Norwegian delicacy.