Christmas is the time of year where you dress up in costumes and eat turkey.
It was invented when The Maker of iSpongebob decided that October 25th was his boss's favorite day to fire people. He decided that if he made a holiday for that day, everybody could keep their jobs. Unfortunately, when he was editing the calendar, the page was on December instead of October, making the day of Christmas December 25th. On October 25th, he was fired.