If you’re looking for something that explains the origins of Boxing Day, well, you’re not going to find it here.

The day-after-Christmas holiday is celebrated by most countries in the Commonwealth but in a what-were-we-doing-again? Bout of amnesia, none of them are really sure what they’re celebrating, when it started or why.

The best clue to Boxing Day’s origins can be found in the song “Good King Wenceslas.” According to the Christmas carol, Wenceslas, who was Duke of Bohemia in the early 10th century, was surveying his land on St. Stephen’s Day — Dec. 26 — when he saw a poor man gathering wood in the middle of a snowstorm. Moved, the King gathered up surplus food and wine and carried them through the blizzard to the peasant’s door.

The alms-giving tradition has always been closely associated with the Christmas season — hence the canned-food drives and Salvation Army Santas that pepper our neighborhoods during the winter — but King Wenceslas’ good deed came the day after Christmas, when the English poor received most of their charity.

King Wenceslas didn’t start Boxing Day, but the Church of England might have. During Advent, Anglican parishes displayed a box into which churchgoers put their monetary donations.

On the day after Christmas, the boxes were broken open and their contents distributed among the poor, thus giving rise to the term Boxing Day. Maybe.

But wait: there’s another possible story about the holiday’s origin. The day after Christmas was also the traditional day on which the aristocracy distributed presents (boxes) to servants and employees — a sort of institutionalized Christmas-bonus party.

The servants returned home, opened their boxes and had a second Christmas on what became known as Boxing Day.

So which version is correct? Well, both. Or neither. No one, it seems, is really sure. Both the church boxes and the servant presents definitely existed, although historians disagree on which practice inspired the holiday.

But Boxing Day’s origins aren’t especially important to modern-day Brits — Britain isn’t known for its religious fervor, and few people can afford to have servants anymore, anyway.

Today’s Boxing Day festivities have very little to do with charity. Instead, they revolve around food, football (soccer), visits from friends, food and drinking at the pub.

Boxing Day has been a national holiday in England, Wales, Ireland and Canada since 1871. For years in which the holiday falls on a weekend, the celebration is moved to make sure workers still get a day off (except in Canada, where it remains Dec. 26), but since visits to Grandma and other family obligations are fulfilled on Christmas, there isn’t anything left to do on Boxing Day except eat leftovers, drink and watch TV.

Just as Americans watch football on Thanksgiving, the Brits have Boxing Day soccer matches and horse races. If they’re particularly wealthy or live in the country, they might even participate in a fox hunt.

The annual Boxing Day fox hunts — which have been held all over the English countryside for hundreds of years — were imperiled in 2005 when Parliament banned the traditional method of using dogs to kill the prey.

Despite the dogs’ limited role (they can still chase the animal, but they can’t harm it) hundreds of thousands of people turn out at Boxing Day fox hunts around Britain.

The Irish still refer to the holiday as St. Stephen’s Day, and they have their own tradition called hunting the wren, in which boys fasten a fake wren to a pole and parade it through town.

Also known as Wren Day, the tradition supposedly dates to 1601, to the Battle of Kinsale, in which the Irish tried to sneak up on the English invaders but were betrayed by the song of an overly vocal wren — although this legend’s veracity is also highly debated. Years ago, a live wren was hunted and killed for the parade, but modern sentiments deemed it too gruesome.

The Bahamas celebrate Boxing Day with a street parade and festival called Junkanoo, in which traditional rhythmic dancers called gombeys fill the streets with their elaborate costumes and headdresses.

And of course, there’s the shopping. England and Canada’s Boxing Day evolved into a major shopping event in the 1980s — the equivalent of post-Thanksgiving Black Friday. But this year, many of the sales started earlier in an effort to boost the slumping economy.

Boxing Day has evolved from a charitable day to an extended Christmas afternoon. It’s a holiday with presents that have already been opened and a dinner that has been eaten.

It’s a holiday best spent lounging around in brightly colored sweaters, wondering, lazily and lethargically, what to do next. Come to think of it, it’s a wonder Americans haven’t adopted it yet.