Boxing Day is celebrated on December 26 by Great Britain, Northern Ireland, Australia, New Zealand, Hong Kong, Nigeria, Trinidad and Tobago, South Africa, and other Commonwealth nations. While there’s no definite answer to why Boxing Day is called “Boxing Day,” the most popular theory is that because household servants worked on Christmas Day in aristocratic England, landowners would give them “Christmas boxes” filled with gifts and food (as well as a day off to visit family) on the 26th.