The second-most important character in the wonderful old comic strip “Calvin and Hobbes” was engaging in a classic negotiating technique, one that sometimes even works.
You ask for something totally unreasonable, just to set a high bar. Then you walk it back, and back, and back some more, until you are asking for something that seems not only normal but, by comparison, hardly anything. And you get it.
Sometimes, as happened with Calvin and his mom, the wishing well has been poisoned — and she is so used to saying, “No, Calvin” — so even a reasonable request gets rejected.