If you've Skyped with me, chances are you have seen me drinking from this mug with a Danish flag motif. (If you haven't Skyped with me, why haven't you? My username is chenywang1102.)
More so than rectangular flags, Danes like skinny pennant flags. It was one of my first impressions of Denmark. In my first hours on Danish soil, I saw many such flags as the train took me from Copenhagen to Århus, crossing much of the country.
It's very easy to buy things with Danish flags on them. The first items that come to my mind are disposable plates and cups and toothpicks with Danish flags. In a supermarket, there will always be plain white plates and Danish ones.
Many exchange students have commented on the Danes' fondness for their flag. It's frequently a topic of discussion, leading to comparisons of flag displaying behavior in their home countries.
Our neighbors to the South, the Germans, are on the other end of the spectrum: they don't display the flag at all. My German housemate told me that if you see your neighbor flying German flag from their house, you first think, "My neighbors are Nazis". The relationship of a people to their history is a fraught one.
One of the Italian exchange students brought an Italian flag with him, which he sometimes takes to parties.
Of course Americans also love their flag, not only to fly the flag but to put the flag motif on many things, like those Old Navy Fourth of July t-shirts.