This is a question that might start becoming more and more common if an article at the Wall Street Journal is any indication:
By Accident or Design, Selling T-Shirts Is Big Business on Web says that the online sales of T-shirts are booming.
‘All over the Web, bloggers, artists and entrepreneurs are unexpectedly finding that T-shirts are more reliable moneymakers than the original ideas that brought them to the Internet.
CollegeHumor.com, a site offering jokes and pictures from college campuses nationwide, sells T-shirts that say “My other shirt has its collar up,” “What Would Ashton Do,” and dozens of others. Its parent company, Connected Ventures LLC, says it takes in roughly $200,000 in monthly revenue from the shirts, about half of its total income. “A year from now things could be very different, but for now, T-shirts are a great way to monetize the Internet,” says Josh Abramson, one of the site’s founders.’
link via an IM conversation with Scrivs