The wearing of green hats in China is strongly associated with infidelity. In fact, in 2015, Shenzhen police used green hats to publicly shame jaywalkers.

The world has become so globalized and interconnected that it’s easy to forget that different cultures hold vastly different perceptions. Misunderstandings remain common across the globe, especially as more people travel to unfamiliar countries.

For example, in Greece and Russia, a thumbs-up gesture might be perceived as an insult, equivalent to the middle finger in other cultures. In some Latin American countries, arriving exactly on time to an event could be considered rude, whereas, in others, being fashionably late is seen as inconsiderate. These cultural differences are the reason travel guides often provide tips on proper etiquette. My Lonely Planet guidebook to Japan, for instance, advises that eating on public transport and wearing shoes indoors are frowned upon. Travelers are also expected to queue neatly and avoid cutting in line.

With thousands of years of history and diverse cultural norms, it’s no surprise that China, too, has customs unfamiliar to many Westerners. Some of these traditions make immediate sense to visitors. For instance, many Chinese consider it impolite to open a gift in front of the person who gave it to you (a mistake I once made in Hong Kong). Additionally, in some Chinese cultures, people are expected to decline a gift three times before accepting it. Another custom holds that finishing all the food on your plate can be rude, as it suggests you're still hungry. By contrast, in the UK, where I’m from, leaving food on your plate might be seen as impolite. These small differences in etiquette can easily lead to misunderstandings or embarrassing situations for first-time travelers.

One lesser-known cultural quirk in China involves the wearing of green hats. Although this might seem trivial to outsiders, wearing a green hat in China signifies that you are a cuckold. An Oakland A’s fan visiting China in their team’s signature green and yellow cap could unknowingly attract stifled laughter. In fact, an American politician from Washington State once toured China, gifting green baseball caps, only to later realize that no one wore his presents because they didn’t want to be seen as cuckolds.

The stigma attached to green hats is so strong that it’s even been used as a form of punishment. In 2015, police in Shenzhen made jaywalkers wear green hats and jackets as part of a public shaming campaign. Offenders were required to assist the police in catching other violators, and their photos were posted on social media. Many jaywalkers opted to pay fines rather than face the humiliation of wearing a green hat.

The reason why green hats symbolize being a cuckold in China is partly shrouded in mystery. It’s not that there’s no explanation, but rather that there are several plausible ones. The most well-known theory traces back to the Yuan Dynasty when the government supposedly decreed that the husbands and male relatives of prostitutes had to wear green hats, marking them publicly. Another similar explanation suggests that during the Tang Dynasty, brothel workers wore specific colors: purple for female workers and green headbands for males.

One of the more eccentric stories involves a husband and wife from centuries, or possibly millennia, ago. In this tale, the husband often traveled for work, and before he left for long trips, his wife would give him a green hat to wear. If her lover saw the husband leave the house wearing the hat, it was a signal that he could visit the wife. Eventually, the village caught on, and the green hat became a source of ridicule.

A more logical explanation lies in a linguistic connection. In Mandarin, the words for "cuckold" and "tortoise" sound similar. The tortoise metaphor is apt because, like a cuckold, the tortoise hides in its shell, seemingly oblivious to the world, including a partner’s infidelity. The green hat may symbolize the green shell of the tortoise.

While the exact origin of the green hat as a symbol of cuckoldry remains unclear, one thing is certain: if you want to avoid snickers or raised eyebrows, it’s best to leave your green hat at home when traveling in China.

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