Receiving a gift is just as much of an art as giving one. There is a proper and an improper way to do it. You have to express gratitude no matter what. No matter if you hate it and plan on regifting it immediately, you need to slap a smile across your face and come up with some nice things to say about it. Because that person put effort into giving you something, and that deserves respect. Even if it’s a sweater that you would never wear in a million years, you should put it on and say «This is niiiiceee» like it’s your favorite gift in the world. This is just the way things are done, and that’s how you keep friends around. But we all learn this at different ages. 

Sometimes it takes kids a while to learn that they should put on a happy face. And some kids just have entitlement coming out of their ears. They usually learn it from somewhere, so you should be vigilant about the influences in their life. You would hate for them to turn out like a brat.