The idiom "another nail in one's coffin" means that an action or event that makes a bad situation worse or brings someone closer to failure or death. It is often used to describe a situation where a person is already in trouble, and something else happens that makes their situation even worse.
For example, if someone is already struggling to pay their bills and they lose their job, that could be another nail in their coffin. It means that their situation has become even more difficult and they are closer to failure.
The phrase is often used in a figurative sense, but it has its origins in the practice of nailing a coffin shut. Each nail that is added makes it more difficult to open the coffin, and therefore represents a finality or inevitability.
In everyday conversation, you might hear someone say "That mistake was another nail in his coffin" to describe a situation where someone has made a mistake that could lead to their downfall. It is a way of emphasizing the seriousness of the situation and the potential consequences of their actions.
• The company's decision to cut employee benefits was another nail in its coffin for retaining talented staff.
• His repeated lies and deceitful behavior were another nail in his coffin for earning the trust of his colleagues.
• I forgot my lunch at home again. That's another nail in my coffin for this day.
• My brother skipped class again, and that's just another nail in his coffin for getting into college.
• The candidate's controversial remarks during the debate were another nail in their coffin for winning the election.
• John's constant tardiness is another nail in his coffin for being promoted to a higher position at work.