The Patriot Act in action

The FBI is warning police nationwide to be alert for people carrying almanacs, cautioning that the popular reference books covering everything from abbreviations to weather trends could be used for terrorist planning.

In a bulletin sent Christmas Eve to about 18,000 police organizations, the FBI said terrorists may use almanacs "to assist with target selection and pre-operational planning."

It urged officers to watch during searches, traffic stops and other investigations for anyone carrying almanacs, especially if the books are annotated in suspicious ways.

The FBI noted that use of almanacs or maps may be innocent, "the product of legitimate recreational or commercial activities."

As Dave Barry would say, "I'm not making this up."