In the software development industry, a death march is a dysphemism or description for the end phase of a project when a hard deadline has to be met, often to meet an arbitrary ship date leaked to the press and/or the shareholders. Often if a project is off schedule due to mismanagement (as many are), said management will ask team members to work especially grueling hours, weekends (sometimes with a straight face), or by attempting to "throw (enough) bodies at the problem" with varying results, often causing burnout. It is also common for a developer to subsist on flat food while in the midst of a death march.
Bill Gates: The world wants and our shareholders need Vista by Christmas!
Steve Ballmer: We have had our developers on a perma death march for the last three years to ship it and need a few more monthes.
Bill Gates: Just drop development of all the useful features and leave the annoying ones!
Flat food is any food item that comes out of a vending machine and can be slid under a door. Flat food is often used by management to subsist software developers slaving long hours to meet a deadline (death march).
I just fed Bob some flat food so that should keep him coding at least another four hours.