A man went to the wine seller’s at midnight to buy wine. The wine seller, hearing several knocks at the door, said without opening it:
“just throw in your coppers through the crack in the door.”
“But,” inquired the man, “how are you going to get the wine out?”
“Through the crack,” was the reply.
At that the man laughed.
“I’m not joking,” said the wine seller, “You see, my wine here is quite thin.”
-Jiang Yingke: Xue tao xie shi(Humourous Stories from Snow Pavilion)