That's what I call the day after someone's birthday. I consider it the day where you get to take care of some stuff, whether work or fun, that might not have gotten attended to properly on your actual birthday.
Usually, for me, it's a day for lingering mischief. Today? Don't know yet, but I have a couple of work-related projects that I'd like to get into tip-top shape. So I'm claiming my +1 Dagger of Ogre-Slaying Day and slaying those last few beasts! Poetry returns on Wednesday!