the final nail in the coffin

US /ðə ˈfaɪnl neɪl ɪn ðə ˈkɔfɪn/
UK /ðə ˈfaɪnl neɪl ɪn ðə ˈkɔfɪn/
"the final nail in the coffin" picture
1.

最後一根稻草, 致命一擊

an event that causes the failure of something that had already been weakening

:
The company's latest scandal was the final nail in the coffin for its reputation.
公司最新的醜聞是其聲譽的最後一根稻草
His decision to quit was the final nail in the coffin for the struggling project.
他辭職的決定是這個陷入困境的項目的最後一根稻草