"On 11 January 2002, retired Marine Corps Gen. Joseph J. Foss of Scottsdale, Arizona, was attempting to board an America West flight bound for Arlington, Virginia, when airport security held him for 45 minutes while they debated what to do with a variety of suspect items he had about his person. This 86-year-old former governor of South Dakota was on his way to attend a National Rifle Association meeting and to speak to cadets at the U.S. Military Academy at West Point, and he carried with him his Medal of Honor, as well as a Medal of Honor commemorative nail file and a dummy bullet which had been made into a key fob.
Each of these items was regarded as a potential security risk by airport personnel: the bullet for being a bullet, the nail file for being a nail file (metal nail files are now banned on flights in the USA), and the Medal of Honor for being a suspicious five-pointed metal object that might have been a weapon (similar to the Japanese throwing discs known hira shuriken).
After being repeatedly searched, Foss was allowed to board the plane with his Medal of Honor, but he had to mail the bullet and nail file home to himself. Foss' experience prompted the piece quoted above, which is the text of a Bob Greene article from the 24 February 2002 Chicago Tribune."
http://www.snopes.com/military/medal.htm
http://www.arizonarepublic.com/special42/articles/0216FOSS16.html
As the newspaper article said, it is indeed hard to teach common sense.