"Bite the bullet," or doing something unpleasant, comes from when soldiers would bite a bullet when they were being operated on without anesthetic.
“咬子弹”（bite the bullet），即做令人不愉快的事。这一习语来源于过去士兵们做手术不打麻药，只能咬子弹忍痛。
There is some debate over whether or not this is true. The phrase has been in use since 1796 and has always meant to have a "stiff upper lip" before doing something you don't want to do.
关于这一来源是不是真的还存在争议。这一短语从1796年就开始使用了，总是用来指在做不愿做的事情时咬紧牙关（have a stiff upper lip）。
It may have come from a belief that people can derive courage from biting a bullet, according to researchers.
研究者称，这也许来自于一种信仰，认为人们能从咬子弹中获得勇气。
