Ah, grad school. Witness this conversation:

Me: Uh, Professor Cohen?
She: (looks at me warily)
Me: The paper for the colloquium...can I hand it in tomorrow?
She: When was it due?
Me: Uh, today?
She: Oh well of course that's fine.

Later the same day, on the steps of Hamilton:

He: So are you coming to my office hours today?
Me: Uh, no? You know the paper I owe you from last semester -- I was wondering -- can I not do it?
He: What do you mean, not do it? What about your grades -- ?
Me: Can I get an R for it? I have more classes than I need.
He: Oh of course, that's fine.

It's mutually beneficial: I don't want to do the papers, and they don't want to mark them. If I were a PhD student I could submit all these papers at the end of six years as chapters of my dissertation...