In the Warring States Period (zhàn guó 战国), Duke Wei of Qi neglected state affairs, for the first three years of his reign, giving himself over to dissipation. One of his minister, Chun Yukun (chún yú kūn)who had a good sense of humor, said to him:”There is a big bird which has neigher taken wing nor sung for three years.” The duke answered, “once that bird starts to fly and sing, it will astonish the world.” The duke thereupon devoted himself to his duties and built his state up into a powerful one. This idiom is used to indicate that a person may rise from obscurity and achieve greatness.

战国时期，有一个大臣叫淳于髡，他身材矮小，但非常有头脑，齐威王继承王位已有三年了，可是他整天饮酒作乐，不理朝政。于是淳于髡想了个激励齐威王的办法。他说：“大王，臣听说齐国有一只大鸟，三年来不飞也不叫，大王知道这是一只什么鸟？”齐威王知道淳于髡在暗喻自己，不由得大笑起来。笑过一阵后，他才说：“此鸟不飞则已，一飞冲天；不鸣则已，一鸣惊人！”从此齐威王勤于朝政，励精图治，国威大振。成语“一鸣惊人”比喻平时默默无闻，突然干出一番惊人的事来。

一鸣惊人 (yī míng jīng rén)
【翻译】Amazing the World with a Single Feat.
【释义】比喻平时没有突出的表现，一下子做出惊人的成绩。
【例句】Jenny平时学习成绩不太好，可是期末考试时却一鸣惊人，夺得了全班第一名。
【近义词】一举成名、一步登天、名满天下
【反义词】身败名裂、臭名远扬、丢人现眼