(We don't celebrate Festivus but this was too funny to pass up. I was looking up pictures of alternate holidays and ran into this classic Seinfeld reference. The picture's website lists their yearly grievances on comics and TV.)
Instead, we celebrate Alternate Holidays. Nobody has expectations or a predetermined vision of these. Since I'm a food person, most of them center around food. My daughter and I normally make some type of decoration but not always. We keep it "in the immediate family" and drop/add holidays at will. It's great!