the final straw的意思是指“压垮骆驼的最后一根稻草，使人最终崩溃的一击”。也就是用来描述让人不堪忍受的最后一件事或者某些原因。

【例句】
Losing my job was bad enough, but being evicted was the final straw.
失去工作已经够糟了，但被房东赶出门后我彻底崩溃了。

She's always been rude to me, but it was the last straw when she started insulting my mother.
她一直对我很粗鲁，但让我终于无法忍受的是她竟然开始辱骂我的母亲。