Celebrated: in the U.S. on January 3, at least since the mid-1990s (origins obscure)
But I'm obviously in the minority, and some people feel pretty violent about this. Since 1995, the town of Manitou Springs, Colorado has held an annual Great Fruitcake Toss, similar to "pumpkin chunking" events held elsewhere in October. Contestants compete on distance, accuracy, and the ability to catch a fruitcake (weighing at least one pound) thrown by a mechanical device. (The rules specify, nothing gasoline-powered – safety first!)
Fruitcakes date back to Roman times, when they were a practical way to preserve and consume exotic fruits out of season. They represented wealth and abundance, and were traditionally used as wedding cakes. Their popularity peaked in England under Queen Victoria, who was especially fond of fruitcake and often served it at tea.
I'm always fascinated by fashions in food. How do foods come into style, and go out? Why don't we eat aspics anymore? (Other than the fact that they're gross, of course.) Will it ever be cool to like fruitcake again?