That's how it is often referred in English

Easter Monday is a holiday in Poland. Wet Easter Monday (Dyngus Day) was traditionally the day boys tried to drench girls with squirt guns, buckets of water, and much more.
http://acweb.colum.edu/users/agunkel/homepage/easter/eastdyn...

The real fun begins on Easter Monday, and in some parts of Poland it goes on for many days or weeks. Easter Monday is the Śmigus-Dyngus Day. It is also called, or rather nicknamed Lany Poniedziałek (Wet Easter Monday) or Świętego Lejka (Saint Drencher's Day). From the early morning until sunset, in all villages, towns and cities of Poland there is a mass dousing frenzy. Every kind of bucket, jug, watering can or squirter is good for the purpose. Groups of young men chase girls and women everywhere and splash them with gallons of water. Young girls are especially the targets of that popular ceremony. They seem to object, squeal and run away from the pursuing youngsters with their "water-weapons". But in fact the girls that haven't been watered down think they've been rejected and are not popular among the boys.
http://www.panoramapolska.ca/index.cfm?NoTot=90&Article=East...