My first thought was "What a funny line!"
My second thought was "How have I never noticed that line before?"
Seriously, has that line always been in that song? 'Cause I don't remember EVER hearing it before. It caught me off guard so much that it actually made me laugh. How I managed to make it through 35 Christmases without hearing that line is a mystery beyond my comprehension.
(and it is a pretty funny sentiment for a Christmas song, when you stop to think about it)