Night Of Ivan Kupala. Belarus, Russia, Ukraine

Kupala Day (Feast of St. John the Baptist; Russian: Иван-Купала; Belarusian: Купалле; Ukrainian: Іван Купала; Polish: Noc Kupały or Noc Świętojańska) is celebrated in Poland, Russia, Belarus and Ukraine currently on the night of 6/7 July in the Gregorian or New Style calendar, which is 23/24 June in the Julian or Old Style calendar still used by many Orthodox Churches. Calendar-wise, it is opposite to the winter solstice holiday Korochun. The celebration relates to the summer solstice when nights are the shortest.
Some early mythology scholars, such as Sir James Frazer, claimed that the holiday was originally Kupala; a pagan fertility rite later accepted into the Orthodox Christian calendar. There are analogues for celebrating the legacy of St. John around the time of the summer solstice elsewhere, including St. John's Day in Western Europe.
The Ukrainian, Belarusian and Russian name of this holiday combines "Ivan" (John — the Baptist) and Kupala which is related to a word derived from the Slavic word for bathing, which is cognate. The latter is reinterpreted as John's baptizing people through full immersion in water (therefore his biblical title of the Baptist). However, the tradition of Kupala predates Christianity, due to correlation to a pre-Christian Slavic god or goddess. Due to the popularity of the pagan celebration that with time it was simply accepted and reestablished as one of the native Christian traditions intertwined with local folklore. On rare occasions it is spelled as Ivanna Kupala (Joann) representing the tradition as feminine.
The holiday is still enthusiastically celebrated by the younger people of the Eastern Europe. The night preceding the holiday (Tvorila night) is considered the night for "good humour" mischiefs (which sometimes would raise concerns of law enforcement agencies). On Ivan Kupala day itself, children are engaged in water fights and perform pranks mostly involving pouring water over someone.