I never jerk at work either. I did it once, when I worked swing shift and it was very early in the morning, no one around. But I wouldn't (and haven't) done it during normal working hours.
For those guys who do it at work, do you try to keep it quiet, or would someone hear you pumpin if they walked in? (When I was in college, I developed several techniques for jacking quietly, so as not to let my roommate hear me at night.)