Dyngus Day

Śmigus-dyngus (SHMEE-goose-DING-goose; also known as lany poniedziałek, meaning "Wet Monday" in Polish; Ukrainian: Поливаний понеділок) is a celebration held on Easter Monday in Poland and Ukraine. It is also observed by Polish diaspora communities, particularly among Polish Americans, who call it Dyngus Day. Similar celebrations are held in the Czech Republic and Slovakia (Oblévačka in Czech, Oblievačka in Slovak, both meaning "Watering") and in Hungary, where it is known as Vízbevető or Water Plunge Monday. Traditionally, boys throw water over girls and spank them with pussy willow branches on Easter Monday, and girls do the same to boys on Easter Tuesday. 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. 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 in Central Europe, and also in the United States, where certain patriotic American elements have been added to the traditional Polish ones.

The celebration has been traced back to the 14th century but may have earlier, pre-Christian origins involving the celebration of the March equinox; The origins of the word dyngus are obscure; it may come from the German Dingeier ("the eggs that are owed") or Dingnis ("ransom"). The occurrence of the celebration across the western Slav countries (plus Hungary, whose inhabitants' forebears conquered a region that was inhabited by Slavs) suggests a common origin in pagan mythology, most likely a link with the Slavic goddesses of fertility. It may possibly be related to the tradition of watering the Corn Mother, who made crops grow and was represented in the form of a doll or wreath made from corn. This would be symbolically drenched in water and kept over the winter until its grain was mixed with the seed corn in the spring to ensure a successful harvest. In time, the growing influence of Christianity in Poland incorporated the dyngus celebrations, along with other pagan practices, into Christian festivals like Easter Monday.

...
Wikipedia