LORELAI: Hey, no one told me it was casual Friday.
Casual Friday, a custom in some offices which allows for a more relaxed style of dress at work on certain Fridays of the year. It began in Hawaii in the mid-1960s, called Aloha Friday, with the idea that workers could wear traditional Hawaiian dress to the office on certain days. By the 1970s, it became acceptable to wear Hawaiian dress every day, but the idea of a more relaxed dress code on certain days spread to California, then to all of the US, and eventually throughout the West by the 1990s.
The Annotated Gilmore Girls 