My favorite airport security fail was at BWI. They have trash cans before you go through security and people always get to these trash cans and realize they brought something they shouldn't have and so they throw it away. Well my wife was waiting to pick me up, because this is on the "unsecured" side of the airport terminal, and she saw several .22 caliber bullets laying on the floor near the trash can. She pointed them out to 2 security guards and one of them asked "What is that?" She had to tell them they were bullets to a gun. I guess they had never seen bullets of different calibers before and just left them lying there. My wife wanted to leave that airport as quickly as possible.