Śmigus-dyngus (Wet Monday) - first written prohibition
1420
Recurring Polish Easter Monday custom of dousing people with water, in which boys traditionally soak girls. The earliest written attestation is a prohibition at the Poznań diocesan synod of 1420, 'Dingus prohibetur', warning against practices where men and women 'attack for eggs and other gifts... or dragging into the water', proof the custom was already well established enough to alarm the clergy.
Source: Wikipedia
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