Introduced in the season-three episode "Depth Takes a Holiday," Holiday Island is an alternate reality accessed through a portal in the back of Lawndale's Good Time Chinese Restaurant. The island itself is a tropical island in which all the trees have died, and is marked by its own Good Times outlet and the Holiday Island High School. Vast stone statues representing holidays loom behind Good Times, of which we see the Valentines Day and Halloween ones.
All known holidays (at least those familiar to Western Civilization) have become live teenagers who attend Holiday Island High School. The holiday teens resemble the most common stereotypes or things associated with their namesakes, but with certain twists (e.g., Halloween is an amateur vandal, and Christmas is tired of being cheery all the time). The biggest holidays, Christmas and Halloween, are the most popular students at the school, though Guy Fawkes Day (a British punk in black leather) is also a member of their clique. The high school is largely populated by colorless nondescript students who are, according to Cupid (St. Valentine's Day), "a bunch of saints' days."
If a holiday leaves the island for too long, their holiday will begin to die out in the human world.
The holidays of Holiday Island are required to be happy at all times and to spread good cheer, which leads Christmas, Halloween and Guy Fawkes Day to (temporarily) escape the Holiday Island reality in protest. In their fortnight away, the school's social scene was taken over by President's Day. After they came back, half of President's Day joined their band, The Holidays.
Some time later, so claims an MTV website flipbook (archived via a fansite), Guy Fawkes Day is trying to get back off Holiday Island and settle on Earth permanently via marriage (or sleeping on someone's couch).
Notable Characters from Holiday Island
- Saint Valentine's Day (a.k.a. Cupid)
- Summary of "Depth Takes a Holiday" on Outpost Daria (via Wayback Machine)