When I was a postdoc at Stanford i simply stopped showing up at the department after 9 months. The chairman later told me that i was the first one in the entire history of the department to have done that. By the way there was absolutely no pressure; they kept paying me and in fact by mistake they raised my salary to $10,000 a month. Then they called me from the payroll office to ask if I would voluntarily return it and I said yes. I did get very depressed though and I became acquainted with all night cashiers in the Menlo Park Safeway that was then open 24 hours.