I'd like to add a few holidays to our already crowded holiday calendar:
Thanksgiving-Up: a day of gratitude for things about which we've said, "Screw it!"
St. Patricks Day After: an international day of barfing.
Immemorial Day: I can't remember what this one's for.
Belabor Day: a day for carrying a joke too far.
In the meantime, here's a song for a holiday that, as far as I know, has never had a song.