Gary Weaver could have told Bill Gates he was about to create an international stink.

On a visit this week to South Korea, the Microsoft founder met with the country’s new president, Park Geun-hye. A photograph shows a beaming Gates and Park engaged in a “one-handed shake,” as it’s become known among South Korea’s sore social media. In that country, one hand in your pocket — wasn’t that an Alanis Morissette song? — means you are hiding something. The grip-and-grin set off accusations that one of the richest men in world was just plain rude.

“I thought, ‘Poor guy, he didn’t mean to do it,’ ” said Weaver, executive director of American University’s Intercultural Management Institute and one of Washington’s global-etiquette gurus. “But it happens; it’s kind of the faux-pas equivalent of passing something with your left hand in the Middle East. It’s considered dirty. It’s your toilet hand.”

The most polite option for Gates would have been a double-clasp handshake.

Weaver is used to warning folks — from State Department families getting ready for their first postings in Nigeria to Beltway contractors cutting deals in Afghanistan.

Bill Gates was Western casual when meeting South Korean President Park Geun-hye on Monday. The hand in his pocket was seen as insulting by some in the country. (YONHAP/AFP/GETTY IMAGES)

Weaver’s institute is part of a nationwide industry of cross-cultural trainers; some work for private consulting groups and others do in-house courses for the State Department and Peace Corps.

They form the United States’ sensitivity soldiers, armed with cultural cautionary tales and a clear mission: Save diplomats and corporate titans from themselves.

For a few thousand dollars, one can learn more than just how to pass out business cards — always with both hands and with the print facing the other person in China! — or why giving the American “A-okay” sign is a no-no in Brazil. (It’s the equivalent of the middle finger in this country. In the 1950s, Vice President Richard Nixon made that gesture while in Brazil and, according to reports, insulted the entire nation.)

But if cultural-etiquette classes are too expensive, there’s always “Essential Do’s and Taboos: The Complete Guide to International Business and Leisure Travel,” the best-selling, cross-cultural bible written by the late Roger E. Axtell, dubbed “an international Emily Post” by the New Yorker. First published in 1990, it includes such helpful hints as, “The hook ’em horns signs in Italy means your wife is cheating on you. You are being cuckolded.”

The industry in recent years has shifted from simply imparting “dos” and “don’ts” to offering more nuanced explanations. “The ‘don’ts’ are touching the tip of iceberg,” said Julia Gaspar-Bates, president of the Washington-based Intercultural Alliances. “Americans really need to understand the ‘whys.’ ”

Cynthia Nerangis, president of Chicago-based LemonLime Consulting, offered an example. “A CEO in Denver asked me, ‘Why do I need to go to Paris to have lunch and talk?’ ” Understanding the whys means knowing that “if you don’t go, you won’t get the business. It develops a sense of comfort and trust,” she said.

In November, cross-cultural trainers and educators will descend on Arlington for the annual conference of the Society for Intercultural Education Training and Research, an event that Gaspar-Bates is co-chairing.

The philanthropist and Microsoft founder also addresses cyber security and the new pope. (The Fold/The Washington Post)

It’s not just Americans who struggle with protocol questions; international business leaders must often adapt to American norms. And what is private and off-limits in one country is not private and off-limits in another, Weaver said.

In India, for instance, acceptable getting-to-know-you questions include: Are you married? What is your salary? And how much do you weigh? (Try these opening lines at your next U.S. Chamber of Commerce networking event.) No surprise, then, that a multimillion-dollar industry has sprung up in India, intent on training young workers to get acquainted with more standardized global norms.

Gates’s gaffe during his three-day visit to South Korea pales in comparison with other international missteps, Weaver said.

Remember when Rep. Bill Richardson, a New Mexico Democrat, met with Saddam Hussein in 1995 when trying to negotiate the release of two imprisoned Americans? Richardson crossed his legs “in that macho New Mexico-style and ended up with his foot in Saddam’s face,” Weaver said. “Hussein immediately left the room. It’s a big insult, like talking to someone and having your finger in your nose. Luckily, Hussein came back.”

Or how about when Bill Clinton traveled to Thailand after the 2004 tsunami and patted the heads of children?

“Heads are considered sacred and not to be touched so casually,” Weaver said.

Yet even Weaver has had Gates-like moments, such as the time he gave a lecture a few years back in Burma (also known as Myanmar) and kept his hands in his pockets the entire time.

“When you are up there,” Weaver said, “you get nervous and you just forget.”