'Hoppy' Birthday Theme for Leap Year Birthday Party

How about a "Sock Hop" with oldies music, old (to them) and ask the guests to dress for the '50's/'60's! Rent some movies from the era, use a lot of cheap crepe paper and balloons, and maybe an ice cream bar with soda glasses for "floats"! Let the kids make their own and have a cake to go with it all! Oh, yeah, the girls must ask their own dates! At that age, they may just want it single gender though!