The multinational group that I sat with included representatives from Sweden, Mexico, Latvia, and Poland, and we had a good time discussing the various traditions by which each culture marks this day and Lent in general. In Latvia, they eat lots of pancakes; in Poland, they celebrate Fat Day on Thursday instead, and I amazed the Pole by knowing about (and pronouncing) pączki ("I'm from Michigan," I explained). The Mexicans did indeed perform the cascarone ceremony on Easter, and they laughed as they recalled, from their teenage years, that as a trick on each other, they would fill their eggs with things like flour instead of the usual confetti.
To further protest Catholicism in Sweden it became a tradition to have semla not just on Fat Tuesday, but on every Tuesday from now until Easter. Semla are absolutely delicious, but I am secretly hoping that I will not be expected to eat one a week for the next month. Woof.
There were about eight or so left over from the coffee break so I brought one home for Joe. However, he ate it before I could take a picture; hence the picture from Wikipedia. Our semla looked just like that, though.