I was performing a complete physical, including the visual acuity test.
I placed the patient twenty feet from the chart and began, "Cover your right eye with your hand." He read the 20/20 line perfectly.
"Now your left." Again, a flawless read.
"Now both," I requested. There was silence. He couldn't even read the large E on the top line.
I turned and discovered that he had done exactly what I had asked; he was standing there with both his eyes covered. I was laughing too hard to finish the exam.