It’s unlikely that you’ll run into Prince William, who’s ducking into Washington on Monday during his whirlwind of a U.S. visit with his wife, the Duchess of Cambridge. The royal couple will touch down on Sunday in New York, where Kate will stay while her husband makes the jaunt south to attend a meeting at the World Bank.

But a meeting could happen (come on — princes roam the streets anonymously all the time, if you believe a canon of films from “Coming to America” to “The Prince and Me”). So, if you do have a close encounter of the royal kind, here’s what you need to know:

First, resist the urge to call him “Wills” the way you might when dissecting the latest US Weekly with your pals. It’s “your Royal Highness” on first reference, and “sir” after that, says Nancy Mitchell, who runs The Etiquette Advocate, a protocol and etiquette consulting firm.

Sooo… fist bump or curtsy? Mitchell says a handshake will do — but wait until HRH extends his royal hand first. “It used to be that we would say ‘don’t extend your hand to royalty,'” she said. “But this younger generation is much more relaxed.”

The new rules of royal interaction call for taking cues from the aristocrat himself.

And there’s no need to bow or curtsy, unless you’re practicing for a curtain call. Mitchell said the moves are reserved for British subjects.

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