Leif Erikson Day is a United States observance occurring on October 9. It honors Leif Ericson, who brought the first Europeans known to have set foot on North American soil and the contributions of Nordic peoples to American society. In 1964, Congress authorized and requested the President to create the observance through an annual proclamation. Lyndon B. Johnson and each President since have done so. Presidents have used the proclamation to praise the contributions of Americans of Nordic descent generally and the spirit of discovery.
Leif Ericson Day is minor in the episode: Bubble Buddy. Patrick wishes SpongeBob Happy Leif Ericson Day and at the end of Bubble Buddy, Bubble Buddy wishes SpongeBob a Happy Leif Ericson Day before drifting off into a bubble taxi. On Leif Ericson Day you say something like "hinga-dinga-durgin" and you wear a Viking helmet and a red beard.