Why do people so often, and completely incorrectly, say they “can’t wait” for things? No one ever says this, it seems, unless they already are waiting for whatever they are talking about.

A seasonal example: “I can’t wait for Christmas!”

When I hear this, I generally point out to people that they are already waiting, and therefore, obviously, they can do so.

What is it with this? Why do so many people say this thing that clearly makes no sense at all?