This person definitely gets it in their post, "The 5 stages of grading".
"Bargaining. This stage usually begins as an earnest attempt to buckle down and grade. The instructor might say, “If I grade five papers, I can watch one episode of House,” or, “For every page I grade, I get to eat a piece of candy.” This process starts well, but as the instructor progresses the amount of work required to achieve the reward generally becomes smaller and smaller..."
You'll have to excuse me now, grades are due in on Monday so I'm off to buy a big bag of Reese's cups!