A common retort to those who seek change in some system or organization, often made by defenders of the status quo. Essentially, the retort is an attempt to stifle such changes (which the retort-er doesn't like), by offering the advocate of change two choices:
In some cases (such as the workplace), bringing about change from below isn't possible--and loving it or leaving it are in fact the only reasonable choices available. In other cases (such as politics in a democratic political system, or one which is claimed to be democratic), advocacy for change is part and parcel of the system, and LoveItOrLeaveIt is a rather unfriendly request.
When it isn't it's a LogicalFallacy known as a FalseDichotomy. -- AaronRobson