Rhett and Link officially confirmed on GMM #1372 [Hilarious Kid's Test Answers] what was previously only alluded to in the latest edition of MYTHICAL MONTHLY and bantered about in various social media posts.
If you spot one in your home town or anywhere along the highway, snap a pic & share it with the Kommunity for fellow MBs to enjoy. A list of "clues" and corresponding locations are being gathered from your contributions and those posted or shared by the "official" Kommunity Facebook, Twitter and/or Tumblr pages.
From the Mythical Monthly posted clues (geographic coordinates) there are at least 43 out there to locate . . . my guess is maybe one somewhere in every state???