City workers in San Diego have been waed ahead of President's Day not to drop any F-bombs -- as in the phrase "Founding Fathers."

The traditional reference to America's patriotic patriarchs is considered gender biased, and a city manual baing the term was reinforced this week with verbal orders, according to legal watchdog group, Pacific Justice Institute.

"We caot allow this type of censorship and PC insanity to destroy our free speech.”

- Brad Dacus, Pacific Justice Institute

“At a time set aside to honor American icons to whom we owe our constitutional freedoms, it is offensive and indefensible that the City of San Diego is directing employees not to even mention the Founding Fathers,” Brad Dacus, president of the Pacific Justice Institute, said in a statement provided to FoxNews.com.

The waing against referring to Washington, Jefferson, Adams and company as "Founding Fathers" first appeared in a section of a city-issued manual titled, “Bias-Free Language.”

Calls to the office of Mayor Kevin Faulconer were not immediately retued.

The Pacific Justice Institute wrote Faulconer on Monday to demand that the guidelines be rescinded, citing more than 1,500 Supreme and lower court decisions that directly invoke the phrase "Founding Fathers."

“We are calling on the mayor to immediately retract these guidelines and reassure city employees that they will not be punished for being patriotic," Dacus said. "We caot allow this type of censorship and PC insanity to destroy our free speech.”

Dacus said any city employee who is disciplined for uttering the phrase can rely on his organization for help.

“The folly of the prohibition is so self-evident that we will offer to represent, at no charge, any city employee who is disciplined or admonished for invoking our Founding Fathers," he said.

Perry Chiaramonte is a reporter for FoxNews.com. Follow him on Twitter at @perrych