Actually one day before Christmas in Finland and other Nordic countries. I don’t know if Linus still celebrates Christmas like that, having resided in the US for a long time already, but the big celebration is here always the 24th of December, and 25th–26th is mostly just resting after it.
The 23rd is the day before Christmas. We celebrate the eve here in the Nordics. The 25th is the relaxing day after Christmas when you eat leftovers and do fuck all all day.