Every half hour in the coal mine, make a shrieking monster noise down the tunnels when nobody is looking. Pretend totally like you didn't do it, and even look a little shocked or confused. Then... drop all of your equipment and scream back up to the workers, "MORLOCKS!!!!" and make screams like you're being assaulted. When the co-workers come down to see what's wrong, grasp your clenched fist firmly to your ear and roll around on the floor shrieking, "ITS GOT ME! ITS GOT MEEEEEEE!!!!"
Every time you do this, they will let you go home early.