The holiday was so named when wealthy people gave their servants and tradesmen their "Christmas box," a gift-filled box in return for working on Christmas Day. Think in terms of Downton Abbey, where the landed gentry lolled away opening gifts and entertaining whilst servants waited on them. In compensation, the servants were given the day after Christmas off and sent on their way with their Christmas box.
More recently, it is often the day when people return their unwanted or ill-fitting gifts to shops. But remember, before you rush back with those socks that didn't quite fit, there is one other use for them, as the lads here demonstrate quite well. If you need to make a closer examination, be sure to click here.