From Wikipedia (I kind of like the description):
"There is no certainty as to the origin of this phrase [the graveyard shift]; according to Michael Quinion it is little more than 'an evocative term for the night shift … when … your skin is clammy, there's sand behind your eyeballs, and the world is creepily silent, like the graveyard.'"
At least I'm drinking some tasty coffee tonight.
