I did not know that yesterday!

The United States has never had a female president, so I had never grappled with this bit of etiquette. Or, to put it another way, there's no precedent for that president.

That said, our first female president will be referred to as "Madam President." This is how female heads of state are referred to in other countries. I can only assume the same rules will apply here. Addressing the president's husband (if she's married) is a bit trickier.

If Hillary Clinton were elected president, we'd most likely still refer to Bill Clinton as either "Mr. President" or "former President Clinton." Even after they're out of office, past commanders in chief retain the title. Call it a perk of the job.

Of course, not every potential presidential candidate is married to a previous ruler of the free world. For example, if Britney Spears were elected to the office (God help us), we'd all address Kevin Federline as "First Gentleman." This is how Dan Mulhern, the spouse of the governor of Michigan, is referred to. Same thing with Jose Miguel Tuason Arroyo, husband of Philippine president Gloria Macapagal-Arroyo.