This wasn't a "thing" when I was in school, but students today use Homecoming Week, Football Fridays, and Spirit Weeks to dress up in crazy themes. Here are some of the ones I've captured this fall before she headed out the door:
Toga.....
Tie-dye/Hippie....
Swim & surf....
Country...
More to come, I'm sure. She raids all the closets in our house the night before, but she does a nice job being creative with what we have on hand.