Leif Erikson Day is a celebration in Bikini Bottom about Leif Erikson, a Viking. It is a similar celebration to Saint Patrick's Day. The differences are that Saint Patrick is a saint, Leif Erikson is a Viking. Saint Patrick's day is in March. Leif Erikson day is on October 9. On Saint Patrick's day, people wear green like a leprechaun They also wear green hats. Leif Erikson Day, people wear Viking hats and dress up like a Viking.