Dress in Avocado green. Dress up like a lawyer (french joke). Serve avocado in every way you can think of.
Everyone brings either 1. an avocado based dish or 2. an avocado.
You don't need to play games because everyone will be too busy eating:
-avocado shakes
-avocado pound cake
-guacamole
-avocado chocolate cake
-avocado tomato sandwiches
-all things avocado
