Watch your mouth -- everyday phrases like "hold down the fort" and "rule of thumb" are potentially offensive bombshells.

At least according to the State Department.

Chief Diversity Officer John Robinson penned a column in the department's latest edition of "State Magazine" advising readers on some rather obscure Ps and Qs.

Robinson ticked off several common phrases and went on to explain why their roots are racially or culturally insensitive. The result was a list of no-nos that could easily result in some tongue-tied U.S. diplomats, particularly in an administration that swaps "war on terror" for "overseas contingency operation" and once shied away from using the word "terrorism."

For instance, Robinson warned, "hold down the fort" is a potentially insulting reference to American Indian stereotypes.

"How many times have you or a colleague asked if someone could 'hold down the fort?'" he wrote. "You were likely asking someone to watch the office while you go and do something else, but the phrase's historical connotation to some is negative and racially offensive."

He explained: "To 'hold down the fort' originally meant to watch and protect against the vicious Native American intruders. In the territories of the West, Army soldiers or settlers saw the 'fort' as their refuge from their perceived 'enemy,' the stereotypical 'savage' Native American tribes."

He singled out another phrase, "Going Dutch," as a "negative stereotype portraying the Dutch as cheap."

And "rule of thumb," he wrote, can according to women's activists refer "to an antiquated law, whereby the width of a husband's thumb was the legal size of a switch or rod allowed to beat his wife."

Further, he explained, "If her bruises were not larger than the width of his thumb, the husband could not be brought to court to answer for his behavior because he had not violated the 'rule of thumb.'"

He went on to urge caution over the word "handicap," as some disability advocates "believe this term is rooted in a correlation between a disabled individual and a beggar, who had to beg with a cap in his or her hand because of the inability to maintain employment."

What to make of all this?

Robinson cited the cautionary tale of Nike rolling out a "Black and Tan" sneaker without realizing the phrase once referred to a group "that committed atrocities against Irish civilians." Nike later apologized.

"Choose your words thoughtfully," Robinson wrote. "Now that you know the possible historical context of the above phrases, perhaps you will understand why someone could be offended by their use. Let us agree that language will continue to evolve with continually improving consciousness and respect for others."

Robinson also serves as the director of the Office of Civil Rights and an adviser to Secretary of State Hillary Clinton on diversity issues. He earlier worked as chief diversity officer with the IRS.