Lany Poniedziałek, also known in English as Wet Monday, is a Polish Easter Monday custom in which people pour or spray water on one another to mark the end of Easter and the arrival of spring. The custom is linked to the older Śmigus-Dyngus tradition and remains a familiar part of Polish spring celebrations, especially among young people and in villages and towns where the water fights are most enthusiastic. Online, the name has become shorthand for that playful soaking ritual, so short clips and memes using it usually appear around Easter and in spring holiday content.