February 29th is traditionally thought to be the day when a woman can propose to her man. In the past, because this day held no legal status, it was ok to to assume that because traditions had no status, women had an opportunity to propose to their men.
Back in the day, in Scotland men would face a hefty fine if they refused, so many did not. The tradition goes back and is linked to an Irish legend, involving St Patrick and St Bridget way back in the 5th century. St Bridget was a nun, who felt that women should be more active in choosing a husband, therefore she petitioned St Patrick on behalf of all women, the result....every four years women can propose to their men.