Terrorists Target Santa Claus: From a 1974 CIA terrorism report:

"A new organization of uncertain makeup using the name 'Group of the Martyr Ebenezer Scrooge' plans to sabotage the annual courier flight of the Government of the North Pole," top U.S. decision-makers were warned. "Prime Minister and Chief Courier S. Claus has been notified and security precautions are being co-ordinated worldwide."

Yep, it was just a joke, but it stayed classified for years anyway.

Details of the memo were only recently revealed after historians compared the censored and uncensored versions of the document and realized the CIA considered a decades-old joke about Santa Claus as a matter of the utmost national security.

"This shows that the system is not about protecting real security issues," said Thomas Blanton, director of the U.S.-based National Security Archive, which made the Santa records public. "The bulk of what government keeps secret is to avoid embarrassment."

If you were a terrorist, would you screw with a dude who knew how to make a sleigh fly? It's a short step from flight to front-mounted Browning machine guns and Sidewinder-toting reindeer. (Big nod to Hit & Run.)