Miller Beer announced it had struck an agreement with the town of Marfa, Texas to become the exclusive sponsor of the phenomenon known as the Marfa Mystery Lights. These are spherical lights which appear south of the town each evening, seeming to bounce around in the sky. They're variously rumored to be caused by ghosts, swamp gas, or uranium (though they're probably caused by the headlights from the nearby highway). Miller announced that under the terms of the agreement the Marfa Lights would be renamed the Miller Lites. The local paper, which was in on the joke, printed the news on its front page.
Comments
Here's a great summary of their history and the present theory on their cause.
http://www.tsha.utexas.edu/handbook/online/articles/view/MM/lxm1.html