When you make a point that is almost a fact and cannot be argued with or about so even if you do argue about it, it's as good as arguing with the wall.
A phrase used mostly by Gen Z that basically means that what you just said was such an undeniable fact that if someone disagrees they are wasting their time and should go argue with their mother.
A phrase used to signal that a person's stance or opinion is not up for debate. Your arguments will not change their mind, so do not attempt to argue with them.