I predict that the world will not end on December 21, 2012, and everyone will suddenly realize that the guy that chiseled that calendar, probably said, "Screw this, I'm tired of chiseling, I'll just call this the end of the world, and so I'll be able to retire from this crappy job."

Edited to add: I had an acquaintance that totally believe the 12/21/12 end of the world prediction. I asked if he believed that a fortuneteller could tell his future, and he said that absolutely not, no one can tell the future. He was not amused when I asked him if he saw the problem with his believing some long dead random Mayan guy could tell the future.