It's not a classic Christmas song, but I love it.
"Christmas Wrapping" by The Waitresses
It really only works as a whole song, but I think this is the coolest line:
"So deck those halls, trim those trees
Raise up cups of Christmas cheer,
I just need to catch my breath,
Christmas by myself this year."
Here's the full set of lyrics if you're interested..
The Waitresses - Christmas Wrapping - Lyrics