Resource books describing holidays. Art supplies to create murals, banners, etc. It's fun to sleep in on cold winter mornings. Students can write a song or poem for their holiday. Students can research the history of a traditional holiday, then invent a history for their holiday.
Students can create a mural using their holiday colors, symbols, foods, etc.
The entire class can vote on their favorite new holiday and have a special celebration complete with food, music, colors, traditions, etc.