Politicians sometimes think they can get away with saying something profoundly offensive or just plain stupid by acting like it was a joke. It never works, just like it didn’t work today when Mr. Romney shamelessly played the birther card in what seems like an increasingly desperate campaign against President Obama. Speaking in Commerce, Mich., about his Michigan roots, Mr. Romney said: “No one’s ever asked to see my birth certificate. They know that this is the place that we were born and raised.” Get it? Everyone knows he’s from Michigan, but nobody is really sure where the president is...