A person wearing a green hat.
In Chinese: 戴绿帽子 (wearing the green hat).
Explanation:
If you are a man, do not, under any circumstances, wear a green hat!
There is an old story in China, about a businessman, a tailor, and the businessman's wife.
(You can guess where this is going…)
Whenever the businessman left his village to go on a business trip,
his wife would cheat on him with the village tailor.
To make it easier for the tailor to know when the businessman was going away,
the businessman's wife asked the tailor to make a green hat for the businessman.
Whenever the wife put the green hat on her husband's head, this served as
a signal to the tailor that the businessman was leaving the village.
Over time, the other villagers figured out what was going on, and they would say to one
another…Tade laopo gei ta dai lv maozi le “His wife has put the green hat on him”
To this day, this phrase is what Chinese people use to talk about wives having affairs.
This phrase is the reason why Chinese men never wear green hats. So, if you are going to China,
whatever you do, don't bring a green hat to give as a gift to a male friend or business partner…
(From: http://an-american-family.blogspot.com/2010/04/dont-wear-green-hat-in-china-here-is.html)