During the time of Emperor Huizong of the Song Dynasty, there was a chancellor named Cai Jing.

On one occasion when Chancellor Cai Jing celebrated his birthday, many students came to wish him well. At this time there was a student who pretended to be him to mix in. And brought a big wooden box as a birthday gift.

Opening that box, only to see that there were dozens of not-quite-flops inside. Cai Jing accepted it with alacrity.

After the ceremony, when the big wooden box was opened again, there was a passage written on the biggest one: "The head is sharp enough to drill, and the belly is empty enough to be greedy. The person in front of the disguise has dignity, but in fact is a big traitor. Not topple, not topple, seemingly easy to fall, but actually two-faced not easy to fall."

Cai Jing read the anger, sent a careful investigation, only to realize that he never had such a student. Only to hold a bellyful of gas, ruthless underlings scolded a pass, the matter is not settled.