If you don't like your situation, and are powerless to change it, leave it. By staying, you are helping perpetuate the situation. By staying, you are also slowly losing your soul.
e.g. Don't complain to your friends about that incorrigible PointyHairedBoss, transfer to a different project or get a better job. Make sure somebody above knows why you left, or your vote does not have the full effect. When you stay, you help that PointyHairedBoss succeed.
But don't give up too easy. Try earnestly to fix things before you give up.
This last point is the one often missed in the political realm, i.e. IfYouWantEuropeYouKnowWhereToFindIt etc. is often stated without accepting/understanding that you might want to try to change the system *here* before giving up on it
Sometimes this phrase has the connotations of LoveItOrLeaveIt. Sometimes a suggestion to VoteWithYourFeet is inferred by the listener to mean LoveItOrLeaveIt.
The name is a joke of sorts, because what it means is voting without voting. For example, you are at a restaurant with a large group. Everyone has finished eating, the check has been paid, and now you are all sitting at the table. You would like the group to move on and go to other places. You could attempt to get everybody's attention, but that would be a lot of trouble. So instead, you stand up. The person you're talking to at the moment follows suit, and you lead him away from the table. The others see what's happening and follow you out. Applied psychology. -- DanielKnapp
I'm told that the concept comes from the Greeks or someone like them. It can also be used to refer to either helping with a project or not, depending on whether you deem the project worthy, rather than arguing for or against it.