怒发冲冠 (nù fà chōng guān)
In the Warring States Period (zhàn guó 战国,481 – 386BC), the King of the State of Zhao (zhào guó 赵国) got an extraordinarily fabulous jade from someone. The ruler of Qin (qín guó 秦国), who reigned a far more powerful country and wanted the rare treasure badly, promising to exchange it with 15 cities. So, Lin Xiangru (lín xiàng rú 蔺相如), an bold and talent minister of the State of Zhao, was then appointed by the king as an envoy to the State of Qin to negotiate with the emperor of Qin. But the ruler of Qin treated him very impolitely and was not attempt to give 15 cities as he previously pledged to do. Lin was pretty angry and humiliated, his hair stood up so stiffly on his head that it lifted up his hat. Since then, this idiom came to be used to mean being extremely angry.