This is the first in a series of where words come from. I ask many times why is it called that, where did a word come from. I am pulling this from memory, so bear with me . The following will all tie together.
A long time in Europe, dishes had lead in them and would cause a person to get very sick and die. Bodies were often found along the road and were buried. A cementary doing their own urban makeover would sometimes open caskets and doing so sometimes would find scratch marks and realized they had buried people alive, this had happened too many times so they changed the rules.
The term "Wake" came from the fact people would gather around for usually 3 days to see if the person would "wake" up from apparent death and be back among the living.
But just to be sure after the funeral someone would be designated to watch over the dearly departed over night just to be sure.
Hence the phrase "Graveyard Shift".
But wait, there would be a string attached to the body which was tied to a bell. If they woke up, the bell would ring and there would be time to pull the body out of the coffin.
Hence the phrase "A Dead Ringer"
See you next time boys and girls!