tit-for-tat以牙还牙；报复。
tit for tat<俚>针锋相对；以牙还牙。相当于an eye for an eye。

【例句】
He was waiting for an opportunity to retaliate.
他在伺机报复。

They had a warm debate and the two gave each other tit for tat.
他们激烈地辩论，二人针锋相对。