Zhang Hei didn't really care about Christmas. He wasn't religious, and he had always assumed that people just used the holiday to have fun. People would decorate their homes on that day, and they would also cook various dishes for the party.
He did think that people just used the holiday as an excuse to party, and that was why he didn't really care about the day before this year.
It was because his birthday fell on that day, and the reason why he waited for that day was because he thought he would be able to celebrate it with Mo Yuan. His mind drifted to Mo Yuan's birthday, but it was just a bitter memory that crossed his mind. They had a big fight that day, and Mo Yuan didn't even know that he had intentionally given him a birthday present that day.