画蛇添足

huàshétiānzú

Meaning:

Draw a snake and add feet

楚有祠者，赐其舍人卮酒，舍人相谓曰：“数人饮之不足，一人饮之有余。请画地为蛇，先成者饮酒。” 一人蛇先成，引酒且饮之，乃左手持卮，右手画蛇，曰：“吾能为之足。”未成，一人之蛇成夺其卮,曰：“蛇固无足，子安能为之足？”遂饮其酒。为蛇足者终亡其酒。（引自《战国策》）

In the country of Chu during the Warring States Period, a man gave his servants a jar of wine after the sacrifice ceremony for his ancestors. His servants thought that the wine was not enough for all of them and thought it would be much better if it was for just one person. So they decided to have a competition with the wine as the award for the winner.

Whoever drew a snake the fastest would win the whole jar of wine. One of the servants drew a snake really fast and finished first. Seeing that the others were still busy drawing their snakes, he wanted to show off his artistic skill, and so added some feet to the snake. At that moment, another servant finished drawing his snake and snatched the jar. He began drinking and said, “How can a snake have feet? I win and you lose.”

This idiom refers to ruining a venture by doing an unnecessary thing.

Example:

这个菜本来很好吃，但是他加了点儿酱油，有些画蛇添足，不好吃了。

zhège cài běnlái hěn hào chī，dànshì tā jiā le diǎnr jiàngyóu, yǒuxiē huàshétiānzú, bùhào chī le.

Example:

This dish used to taste so good, but after adding some soy sauce “Hua she tian zu” - it is not so delicious.