I didn't believe it until I saw it myself: My friend asked me to bring red and blue plastic cups to Sweden because the U.S. students really miss them. It's true. Here's why. (This needed to be explained to me because this was a part of U.S. college life I missed out on.)
These cups are valuable because they are opaque. This allows you to walk down the street with a beer without anybody (anybody = police) being able to tell that you have a beer in your hand, which would otherwise be a violation of open-container laws or evidence of underage drinking. As a result, the plastic cups have been synonymous with college drinking.
That's why the U.S. students miss them so.
In other news: Stockholm basically closes at 4pm on Saturdays.