Valborg!

from wiki: "In Sweden, Walpurgis (Swedish: Valborgsmässoafton or Valborg) is one of the de facto public holidays during the year. Sir James George Frazer in The Golden Bough writes that "The first of May is a great popular festival in the more midland and southern parts of Sweden. On the eve of the festival, huge bonfires, which should be lighted by striking two flints together, blaze on all the hills and knolls". The tradition which is most widespread throughout the country is probably singing songs of spring. Most of the songs are from the 19th century and were spread by students' spring festivities. The strongest and most traditional spring festivities are also found in the old university cities, like Uppsala and Lund where both current and graduated students gather at events that take up most of the day from early morning to late night on April 30, or "sista april" ("The last day of April") as it is called in Uppsala."