I don't exactly know why but I have heard it is because you get bad luck or something.

I never heard of that. You mean people aren't supposed to wear anything white after Labor Day? When are people allowed to wear white again?

"As with many customs and etiquette dictums, it's difficult to pin down the reason behind the prohibition against white after Labor Day. We searched on variations of "wear white after Labor Day" and sifted through the Etiquette and Fashion categories in the Yahoo! Directory. We managed to turn up a bit of information on the fashion dictate.

Originally, the rule was more along the lines of "Only wear white shoes between Memorial Day and Labor Day." Furthermore, it mainly applied to white pumps or dress shoes. White tennis shoes and off-white boots seem exempt, as are any shoes worn by a winter bride. "Winter white" clothing (e.g., cream-colored wool) is acceptable between Labor Day and Memorial Day too.

The only logical reasoning we could find cited temperature. Image consultant Nancy Penn suggests that because white reflects light and heat, wearing white would make you cooler in winter, and thus should be avoided. But others suggest the rule stems from a class issue. Acting Director of the Museum at the Fashion Institute of Technology Valerie Steele notes that in the late 19th century and the 1950s, more people were entering the middle classes. These nouveau-riche folks were often unaware of the standards of high society, so they were given specific codified rules to follow in order to fit in.

Several sites quoted a charming refrain about G.R.I.T.S. -- girls raised in the South. This bit of folklore states, "Southern girls know bad manners when they see them," and a clear sign of bad manners is wearing white shoes before Easter or after Labor Day. Because fashions in the American South can be a little more formal than elsewhere, perhaps the no-white-shoes rule came from south of the Mason-Dixon Line? Even Star Jones (an otherwise fashion-forward Southern lady) admits that white shoes "are for Easter Sunday and not the dead of winter."

We can only surmise that the point of this rule is to ensure that people only wear summer fashions during the actual summer months. The opposite probably applies as well, but people generally don't need to be reminded to avoid wearing a goose-down parka in 100-degree weather. If you live in a locale with summer temperatures year-round, we can't see the harm in wearing white shoes or a head-to-toe white outfit in October. And we promise not to tell Miss Manners."

oooooooooh :p