  So Angry That One' s Hair Lifts Up One' s Hat 怒发冲冠

  In the Warring States Period, Lin Xiangru, chief min-ister of the State of Zhao, was sent as an envoy to the State of Qin to ask the ruler of Qin to return a fine piece of jade to Zhao. But the ruler of Qin was rude and unreasonable. Lin was angry, and his hair stood up so stiffly on his head that it lifted up his hat. 
  战国时代，赵国的大臣蔺相如出使到秦国。在他向秦王索回玉璧的时候，秦王蛮不讲理，蔺相如气愤得连头发都竖了起来，向上冲着帽子。

  This idiom came to be used to mean being extremely angry.
  后来人们用"怒发冲冠"这个成语形容人愤怒到了极点。