Moving the goalposts, sometimes also called 'raising the bar' or 'demanding impossible perfection', is a logical fallacy in which previously agreed upon standards for deciding an argument are arbitrarily changed once they have been met.
Instead of reconsidering their position or admitting defeat in light of new information, the goalpost movers demands from an opponent that he or she address more and more points after the initial counter-argument has been satisfied.
Almost inevitably, this back and forth will lead to the goalpost mover making an impossible request for proof.
Cowboys fans of course are no strangers to this fallacy, especially as it pertains to Dak Prescott.