Today is boxing day.
Once upon a time, there was a thing called a Christmas box. A Christmas box was a box with a small hole cut in it, like a piggy bank, through which coins could be dropped. It was kept in a church and, like a piggy bank, it could not be opened, only smashed. The smashing was done at Christmas, hence the name: Christmas box.
Christmas boxes were used by servants, apprentices, bloggers and other impoverished fools to save up some money for the frosty and festive season. In gambling dens there would be a Christmas box of tips for the benefit of the butler. As one chap put it in 1634:
It is a shame, for a rich Christian to be like a Christmas boxe, that receives all, and nothing can be got out, till it be broken in peeces.
Anyway, in the eighteenth and nineteenth centuries the idea of the Christmas box shifted. There were lots of fellows like postmen and milkmen and butchers’ boys and bloggers who didn’t have loose change to be stowing away all year. Yet they still felt they deserved a little something at Christmas. So generous Victorians would make a little box of presents which they would present to all the delivery boys on the first weekday after Christmas, so sayeth the OED.
The first weekday after Christmas therefore became known as Boxing Day.