Draw a Snake and Add Feet to It 画蛇添足
Long long ago, several people had a jar of wine among them and all of them wanted to drink it by himself. So they set a rule that every one would draw a snake on the ground and the man who finished first would have the wine. One man finished his snake very soon and he was about to drink the wine when he saw the others were still busy drawing, so he decided to draw the feet to the snake. However, before he could finish the feet, another man finished and grabbed the jar from him, saying, "Who has ever seen a snake with feet?" The story of "Draw a snake and add feet to It." tells us going too far is as bad as not going far enough.