Tin foil hat
Chicken/Turkey based hat
Like a helmet but with horns on it (myself preferring more of a bull-esque look to it)
Giant sock hat (christmas stocking style optional)
Plant pot hat (plant is compulsory)
Crown (we be can royalty!)
Laurel wreath (the same kind of wreath you see on depictions of roman emporers)
Fun hat suggestions. My personal fave is tin foil hat.