And their mother says, "Say thank you, Robbie"--or Jenny, or Mindy, or whatever.
[At least that's the way it was when I was growing up. Nowadays parents seem oblivious to their kids' manners.]
Here's the lesson. It's not that the child isn't appreciative of your gift. He--or she--is dying to open it, to see what it is. Their heart is racing, adrenaline is flowing, endorphins are kicking in. They can't wait.
Mom, on the other hand, is all about social mores. "Say thank you."
So the kid does, kind of halfheartedly, or maybe a bit shyly if they're older. They'll feel a little embarrassed for the greed they feel, for the desire to get it over with and tear the damn thing open. And you'll nod, say they're very welcome and you hope they enjoy the toy--or book, or sweater, or whatever. You'll turn back to the mom, release the kid to the freedom of shredding paper and ribbons and plastic wrap and cardboard.
I don't think the child is wrong. That carpe diem of tearing gifts open, of getting excited over wrapping, over ribbons, is a wonderful thing. But I think Mom's lesson is pretty powerful. "Say thank you." Not because it's socially required, not because the gift-giver deserves the thanks, although they certainly do. I think it's important to say thank you because that pause of contemplation gives the gift depth.
In the hedonism of "a gift! a gift! a gift!", we forget to appreciate the moment. Moments pass so quickly. Saying thank you is a nod, however brief, to acknowledge it. Before it's gone.
Happy Thanksgiving, USA.