Before going that far, workers should consider explaining less. If you tell people why you can't work overtime, they will trivialize your outside commitments. If you "have another commitment" then they can't argue with the substance.

Of course your boss could still threaten to fire you, if it's the US with shitty labor law. But be smart, and stop providing the argumentative material to them.

Similarly, just don't answer the phone or text messages on your day off. Don't friend your boss on social media... If that's your baseline, again, they have less information to use against you, and all of the pointless arguments simply stop happening.

This is all surprisingly easy to do if you plan it out in advance. The key point is that your boss is not your friend and the company is not your family.