You can find a Christmas sweater at many department stores or specialty shops. If you're looking for something unique, you might try checking out Etsy or other online retailers for handmade or vintage options. Additionally, you might consider borrowing one from a friend or family member if they have one that they're willing to lend you. Finally, you could always make your own Christmas sweater using supplies from a craft store and your own creativity. Whichever way you choose, make sure it's something that brings you joy and fits the holiday spirit!