Interestingly, there are categories of habitual liars (as distinguished from pathologic liars) who have no fear of common knowledge whatever. They lie in preference to telling the truth, and if caught, suffer no embarrassment or remorse. I once encountered such a person who was telling a story about a Wildlife Officer using an AK-47 assault rifle to kill a grizzly bear in West Virginia. When informed that no wild grizzly has ever been reported east of the continental divide, and that a state agency certainly would not issue a Russian weapon to its officers, the person simply continued, "Yeah, he was firing on full automatic from the hip, and the grizzly would have gotten him if he had only a pistol." See: http://www.answers.com/topic/pseudologia-fantastica-1?cat=health