This is a harder one to explain but an awesome tradition that contributes to all of december feeling special and not just the christmas days. In Alex's opinion 'Christmas' as a concept refers to the 24th and 25th of December. On the other hand 'Christmas' to me starts on the 1st of december. How could it not when there's a million christmassy things to do all throughout the month?
So, the 'Christmas TV-calendar' is basically a TV show with 24 episodes showing from 1st to 24th of December. They're mostly for kids although we have hilariously inappropriate adult versions too. Each year there's usually shown both an old show and a completely new one never seen before.
The concept is what's interesting: The time in the TV show accounts to real-time. As so the first episode takes place on the 1st of December in the actual storyline. We follow the main character from the 1st of december through the month. The theme is always something christmassy like a search for a disappeared Santa Claus or stopping some villain from sabotaging Christmas. The shows have grown increasingly more modern over the years - this year the new show is about a kid traveling back in time to make sure time-traveling is invented in the first place... I'm sure there's a christmas theme in there somewhere...