This idea was submitted by the woman who threw the most awesome Geek Baby shower ever! I hope it helps you with your party decor!
This hat is made out of paper bags, cardboard, some sort of stuffing (she used plastic shopping bags), tape, and paper mache.
1. Cut cardboard in a circle the size of the brim of the hat.
2. Take a brown paper bag and make the shape of the top.
3. Fill it with plastic bags.
4. Draw where you want the face.
5. Tape chunks of paper bag to make the shape of the face.
6. Then paper mache over everything.
I hope this helps you for your party decor!