SLAVE DRIVER - is someone who makes unreasonable demands on your time, resources, and attention.
Slave Drivers are almost always people you report to. Who else has the authority to make huge demands on you? The demands themselves may vary: Slave Drivers may expect you to accomplish enormous amounts of work in incredibly short time frames, or they may simply want you to spend vast amounts of time working. They may expect you to achieve results (such as an exponential increase in sales) that are simply beyond reason, or they may expect you to put your personal life aside for the sake of the business. When it becomes impossible to keep up with the pace or the sheer volume of work, you know you are dealing with a Slave Driver.