Actually, I always thought it was more like this: (click on the picture to see the larger version.)
But I did learn something - Sadie Hawkins Day doesn't fall on Leap Years - but on the first Saturday after November 9th. Bachelors beware!
In the Li'l Abner comic strip, Sadie Hawkins was the daughter of one of Dogpatch's earliest settlers, Hekzebiah Hawkins. When she reached the age of 35, still a spinster, her father in desperation called together the eligible bachelors of Dogpatch and declared that day to be Sadie Hawkins Day and that "when ah fires [my gun] all o' yo' kin start a-runnin! When ah fires agin - after givin' yo' a fair start - Sadie starts a runnin'. Th' one she ketches'll be her husband."
The town spinsters decided that this was such a good idea, they made Sadie Hawkins Day an annual event, much to the chagrin of Dogpatch bachelors everywhere.