Apparently, the man had been suffering from severe headaches but didn't know the cause of his pain. How could you not know there was a four-inch knife blade in your skull? Full story.

AP
This photo taken on Feb. 13, 2011 shows the x-ray scan of Li Fuyan at the People's Hospital in Yuxi in southwest China's Yunnan province. Surgeons in southern China successfully removed a rusty, 4-inch (10-centimeter) knife from the skull of the man who said it had been stuck in there for four years, the hospital said Friday, Feb. 18, 2011.