This is one of those misbehaviors that while, your child shouldn't do it, it kind of isn't his fault. Everywhere we go we are bombarded by what we need and what we should want -- happy children playing with toys on t.v. and on the pages of magazines. And during the holiday season, what's the question they get asked the most? "What do you want for (insert your holiday of choice here). Still, there should be some limits. Whether you are buying the gifts or Santa is in charge of them let your child know that while you realize the things he is asking for is important to him, he won't be able to get everything that he wants. Talk about how gifts during the holiday season are just one way we are able to do something nice for the people that we love and care about, but there are other ways that make us feel good inside too.
Then act on it. Go to the store and pick out a gift or food to donate to a less fortunate family. Have him make a holiday card for a relative -- anything that focuses on the sprit of the holiday and not the material aspect.