David Edgerley Gates
Back when I lived in Provincetown, my pals Skip and Katrina celebrated Boxing Day. Skip hailed from one of the border states, and Katrina was a Scot. He'd once made it to the semi-final tables of the World Series of Poker, which is one of those things you can only marvel at, it seems so far beyond the orbit of mere mortals, but that's a different story. When they invited me to their Boxing Day party, I'd never heard of such an event. And when I hastened down to their house on a chilly winter's eve, her dad was waiting just inside the door, kilted up in full tartans and playing the bagpipes. It was epic.
The day after Christmas is a feast day in the liturgical calendar, St. Stephen's. This somehow got transmuted into a general alms-giving, when "post-men, errand-boys, and servants expect to receive a Christmas-box." (Hyphens in the original, from the OED, 1830's.) An earlier tradition is apparently that servants in a wealthy household, working over Christmas, got the next day off to spend with their families. The etymology is that you were often given a box of party favors to take with you.
Snopes goes the conventional wisdom one better. They say the common thread is charity to somebody lower on the social scale than you are. Equals exchange gifts on Christmas Day. Tradesmen, employees, the less fortunate, get theirs the day after; neither do they reciprocate, which would presume an equivalency. In other words, Boxing Day reinforces the class system.
Be that as it may, and there are competing theories, it's a big deal in Great Britain and the Commonwealth. Retailers schedule annual sales around it. Sports leagues schedule test matches. The common folk schedule industrial drinking. The estimable Ali Karim, of Shots magazine, a confirmed gin man, suggests that an Asian pear or three eaten beforehand will increase your stamina, and give you less of a thick head the day after. I can't speak to this. If he's proved right, I bow to genius.
Oh, and lest we forget. Good king Wenceslas looks out, on the Feast of Stephen, when the snow lay round about. And sees a poor man, gathering wood for a fire. The king puts together a gift box. Bring me flesh, and bring me wine, bring me pine logs hither. He and his page go out into the weather, food and drink and wood, to warm the peasant's hut. The lesson of the story is, Ye who now will bless the poor, shall yourselves find blessing.
Raise a glass. Be of good purpose. Bless us, every one.