Halloween group costume Ideas...?

I know its a totally out of season, but I need a really good idea for a group costume. There has to be at least 2 guys and 2 girls. (we can always get more people involved though) Last year we were the Scooby Doo gang, we've also gone as Mario Kart characters. Any good ideas? I thought about Gilligan's island, the clue characters or The Flintstones.. but I want something more original.