It's from Frieren. The episode where the demon army is having "peace talks" with the king in order to get him to lower the barrier protecting the castle.

Frieren explains that the demons don't actually communicate with words, to them they are nothing more than magic words that when said in the right combination get you to do what the demon wants you to do. Since the demons are predators of humans, this usually results in the death of the humans.

The real world analogue to this is the third worlders calling you racist when you object to their rabidly anti social behavior. They do it because they know they can influence your behavior with words like these, even though they themselves don't believe a word of it.

Whites are the only group of people who modify their behavior when someone calls them racist. That is why nonwhites use it. None of the nonwhite groups actually believe in equality or colorblindness or any of that liberal nonsense. It is literally them gaming the system to their advantage. They can use it to get money from lawsuits, use it to get promoted at work, use it as a shield against criticism, or in the recent case in England, use it to manipulate the police into arresting a man they stabbed instead of being arrested themselves.

There is a video that I can't find at the moment of an african migrant who doesn't speak English just repeating the word gib over and over again because he knows that if he says that word, the white female social worker will give him money, and he assumes it will work on the cameraman too.