Put a nail in someone’s coffin

To put or hammer a nail, or sometimes the final nail, in someone’s coffin, is to bring that person close to disaster, defeat, and sometimes even death. The expression can also be applied to issues, states of affairs, or contests. The expression has always been figurative and dates in these senses since the late 18th century, although, of course, the literal hammering of nails into coffins had been going on for centuries before this. ‘Coffin nails’ is also slang for cigarettes and this usage is first recorded from the late 19th century, less than fifty years after their introduction.