It has a big hand printed on the front with the zipper between the middle and ring fingers. Guess what happens when it's partway unzipped.
http://www.wired.com/geekdad/2010/09/threads-for-trekkies-traditional-greeting-hoodie/
http://www.wired.com/geekdad/2010/09/threads-for-trekkies-traditional-greeting-hoodie/