If you want to wear your mind on your sleeve, consider buying a philosophy t-shirt. If you just type "philosophy t-shirt" into Google or another search engine, you'll come up with lots of hits, many of which have to do with a certain brand of cosmetics or "philosophy" in some general sense. The purpose of this lens is to help you identify places where you can find philosophy shirts for the serious philosophy lover.
There are definitely lots of sources out there, and so this page will only mention a few of my personal favorites. Rest assured that you have more choices than what its presented below. If these don't tickle your fancy, start Googling philosophy t-shirts and see what you find.
Quote shirts are by far the most popular philosophy shirts - these generally sport a picture of some thinker along with some pithy or otherwise remarkable quote that is representative of the thinker's philosophy.
There are a number of places where you can get philosophy quote shirts, but the Philosophy Gift Shop stands out as having a diverse line of high-quality products. If your favorite philosopher can't be found among their wares, then you have pretty rare tastes. The Philosophy Gift Shop boasts the broadest and best collection of philosophy quote shirts on the market today, offering an unparalleled variety of philosophy shirts with quotes from famous philosophers. They also have products geared towards scientists, mathematicians, and religious thinkers.
While somewhat less popular than quote shirts, philosophy humor shirts provide great laughs for the in-crowd that get them. If you go this route, expect people who get the joke to find your threads hilarious, while others will stare at you quizzically.
SagaciTee offers a number of clever philosophy t-shirt designs that will tickle your funny bone, inlcuding offerings that poke fun at Thales, Aristotle, and deconstruction. The graphics are attractive, original, and a refreshing departure from the oftentimes serious world of t-shirt wisdom. As a relative newcomer to the world of philosophy shirts, SagaciTee is adding new designs regularly.
While the Philosophy Gift Shop and SagaciTee have specific emphases, other vendors offer a more-rounded sampling of philosophy shirts. EpistemeLinks offers quote shirts, humor shirts, and a few other things that are hard to classify (e.g., the principle of identity emblazoned on your chest). Thye also have a helpful products page that points you to philosophical offerings at other sites. If you want to cast an even wider net, just do a search for Philosophy at CafePress or at Zazzle.