Odd Number

• Paint the number 3 onto a shirt with fabric paint. Then mess up your hair, wear mismatched socks, and do any other strange things to your attire and makeup. Voila -- you're an odd number. Of course, any odd number would work if you'd rather wear 7, 15, etc.
  
  

PIe Chart/Bar Graph

• Attach two large pieces of card stock together so they can be worn like a sandwich board over your shoulders. Print and cut out pictures of different pies or draw them on in bold markers. Label the pies and tell people you are a pie chart. Similarly, but for adults only, make the sandwich board into a "bar" graph and graph how much time you spend at different bars or rate how much you like different bars.
  
  

Calculator

• Use a large cardboard box from an appliance, large speakers etc. Cut a hole in the top front like the display panel in a calculator and cut off the bottom flaps for your feet to stick out. Then draw on all the buttons for the keypad. You can make your calculator a complicated graphing calculator or a simple desk calculator.
  
  

Pumpkin Pi

• Acquire any sort of pumpkin costume, or just buy an orange sweatsuit or a T-shirt. Write out in fabric paint as much of the number pi as you can fit on the costume or orange shirt. Tell people you are "pumpkin pi."
  
  

Group Costume: Pi or Number Line

• If you are part of a math department or a group of math-loving friends, you can dress up together as the number pi. Simply make T-shirts with the digits of pi and have one person wear the 3, another wear the decimal point, another wear the 1, etc. You can continue this costume for as many colleagues or friends as you would like. Similarly, a group of people can wear numbers and be a number line when they stand in a row.