Si hoc legere
Si Hoc Legere Scis Nimium Erutionis Habes
Roughly translated, "If you can read this, you have too much education." When I wear this in the U.S., most people look at it and ask what it means. In the U.K., by contrast, people read it and laugh.
My Mom got this for me, I think from Signals or Wireless.
(T-shirt copyright Softwear Toys & Tees)