One who is shot at with a gun is said to 'eat lead'; as an exclamation, the phrase is directed toward the intended target.A bullet is made of lead so when a gun is fired at someone, the intended target might be 'eating lead' - that is, bringing the bullet inside their body.

eg:  "Eat lead!" yelled the bank robber as he fired his gun at the police outside.

Note:

由于子弹是由铅做成的，所以“吃铅”的意思就是“吃枪子”，也就是让你尝尝我的厉害。

例：银行抢劫犯一边对外面的警察开枪一边说：“尝尝我的厉害”。