Walpurgis Night, a traditional holiday celebrated on April 30 in northern Europe and Scandinavia. In Sweden typical holiday activities include the singing of traditional spring folk songs and the lighting of bonfires. In Germany the holiday is celebrated by dressing in costumes, playing pranks on people, and creating loud noises meant to keep evil at bay. Many people also hang blessed sprigs of foliage from houses and barns to ward off evil spirits. The origins of the holiday date back to pagan celebrations of fertility rites and the coming of spring. After the Norse were Christianized, the pagan celebration became combined with the legend of St. Walburga, an English-born nun who lived at Heidenheim monastery in Germany and later became the abbess there. Source: https://www.britannica.com/topic/Walpurgis-Night