T-shirts bearing the phrase I'm With Stupid and an arrow pointing towards the person standing next to the wearer first appeared many years ago. Originally a pretty good joke, the slogan suffered the fate of many pop culture jokes by becoming a cliche, but then enjoyed the fate of all cliches by becoming ironic, and thus cool all over again.
During a 2007 visit to the USA by the Queen of England, crowd members were told not wear I'm With Stupid T-shirts in case they offended the royal guest, showing just how much this slogan has soaked into the American culture. What other specific t-shirt slogan has been singled out for a royal ban!