Well, that's an easy one. First, you need to find some really ugly fabric. Make sure it's something that no one in their right mind would ever want to wear. Then, add some cheesy Christmas decorations like reindeer, snowflakes, and Santa Claus. Don't forget to put the ugliest buttons you can find on it. And if you really want to make it special, you can add some tinsel to really make it stand out.