This is a technique used by managers in an attempt to maximize the productivity of their subordinates. A manager intentionally assigns too much work or moves up deadlines until a subordinate either (a) refuses to accept the assignment, or (b) fails to complete the assignment on time.
Using this technique, a manager hopes to discover the following:
As a subordinate, the best way to deal with a manager who uses this technique is to keep careful track of all the commitments being made, and when they approach the "undoability" level, talk about them with the manager. Don't get upset, don't try to do everything being asked, and don't quit without first trying to negotiate a reasonable amount of work.
Whether this technique is a good one is debatable. It is tough on subordinates who don't know how to deal with it. It is manipulative. But it can help managers determine what their subordinates are capable of, and to what extent they can manage themselves.
As a manager, this is OK if you tell your team that's what you're doing. I make it clear that if they can't get the work done because I've given them too much, it's my problem to fix - but it is their problem to tell me I have a problem to fix. Done in this way, I don't think it is manipulative. -- PaulHudson
This is also the technique we use for boarding subway cars in New York. The latest subtlety is to do the pushing with your briefcase, bag or backpack, and to always say "excuse me" before elbowing someone clear out of your way. It's only polite, after all. -- WaldenMathews
See also TheOneMinuteManager