CSI: NY, Season 4

(while working the late-late shift in the cemetery)

Grave Digger #1:
Smallpox, Yellow Fever, influenza. She had the Bubonic Plague.

Grave Digger #2:
(digging) What are you talking about, Pops?

Grave Digger #1:
Long ago when several coffins were excavated and scratches were found inside, our ancestors, they realized they'd been burying (snickering) folks before their time. No kiddin'. Back then, when the plagues hit, guys like you and me, we couldn't dig fast enough.

Grave Digger #2:
(not believing) Come on!

Grave Digger #1:
Saved by the bell doesn't mean what you think. Morticians would tie a string to the hand of the dead person and take the other end of the string and tie it to a bell, aboveground. And immediately after the, uh, burial, a person from the mortuary would be assigned the task to sit by the new gravesite and listen for the bell to ring. (laughs) That was called the graveyard shift.