Traditionally, boys throw water over girls and spank them with pussy willow branches on Easter Monday, and girls do the same to boys. This is accompanied by a number of other rituals, such as making verse declarations and holding door-to-door processions, in some regions involving boys dressed as bears or other creatures. The origins of the celebration are uncertain, but it may date to pagan times before 1000 AD; it is described in writing as early as the 15th century. It continues to be observed throughout Central Europe, and also in the United States, where certain patriotic American elements have been added to the traditional Polish ones.