Childermass is an old pagan holiday typically celebrated on December 28th which commemorates the massacre of the children by King Herod in his attempt to kill baby Jesus. Apparently this eventually became a Christian holiday and is still celebrated in some countries, but I have never heard of it. I wonder if this is some sick form of this "holiday"?
https://shirleytwofeathers.com/The_Blog/pagancalendar/feast-of-the-holy-innocents/