If you’d like to proudly wear your GIS-Geek status on your sleeve (or chest) and show a sense of humor at the same time, you might want to check out http://www.gisnuts.com/. They have T-shirts with sayings such as:
“Raster Master“
“I survived a datum shift”,
“NAD83 – We’re not in Kansas anymore“,
and “Never Make Cartographers Mad. They’ll tell you where to go and draw you a map!”