The students often works the graveyard shift to post their groaners on their site. After all, the early bird gets the worm!
In the 1500s, England considered itself to be running out of places to bury people. So they would dig up coffins and take the bones to a bone house and then reuse the grave. When reopening these coffins, one out of 25 coffins were found to have scratch marks on the inside, and they realized that they had been burying people alive. So they thought they would tie a string on the wrist of the corpse, lead it through the coffin and up through the ground and tie it to a bell. Someone would have to sit out in the graveyard all night - graveyard shift - to listen for the bell. Thus, someone could be saved by the bell or was considered a dead ringer.