Question about December 23

[DemonsAreOurFriends]

I suppose it's a little late to ask, but what exactly is the significance of December 23? The HPs have said that it's Father Satan's "personal day" but that's not much of an explanation. What exactly are we meant to celebrate/observe?

 

[FlamingRedRose666]

I've heard from other SS saying it's Father Satan's birthday.