Thinking inside the box

I've often wondered why the day after Christmas is called Boxing Day in countries of the former British Empire. The best answer seems to be that it's the first day after Christmastide that every errand boy was given his 'Christmas-box', a gratuity as thanks for providing good service all year. They didn't get it until after the Christmas Day festival in case they used it to get pissed and couldn't be arsed to deliver the turkeys.

My theory is it's the day your rubbish bin overflows, and for once, those outrageously large Amazon boxes are put to proper use.