Leap day - February 29th
February 29 is a date that usually occurs every four years, and is called leap day. This day is added to the calendar in leap years as a corrective measure, because the earth does not orbit around the sun in precisely 365 days.
It is a tradition that women may propose marriage only on 29th February. There is a fine if a marriage proposal was refused by the man. In Finland, the tradition is that if a man refuses a woman's proposal on leap day, he should buy her the fabrics for a skirt.