Ugly Sweater

The chance out of any single present is small, so opening them one at a time as they drop wastes the event. Stockpile presents through the whole Christmas period and tear through the pile in one sitting. The odds get slightly worse once your world has gone into Hardmode, which is an argument for doing your opening early if you have the choice.

The joke is the real world habit of being handed a knitted holiday sweater you would never have bought yourself, then wearing it anyway because your relatives are watching.