Boxing Day, as a child I thought this day was reserved for all the siblings to fight over their gifts.
“Ray and Sally are having a boxing match over that car!”
However according to Wikipedia;
Boxing Day is a holiday celebrated on the day following Christmas Day, when servants and tradesmen would traditionally receive gifts known as a “Christmas box” from their masters, employers or customers, in the United Kingdom and Commonwealth nations. Boxing Day occurs on 26 December, although the attached bank holiday or public holiday may take place either on that day or a day later..