There are some
Christmas printables here. And MES has
Christmas bingo games and
Christmas worksheets with mazes, crosswords, word searches etc.
Christmas coloring pages to give out are also nice. For younger kids, you could even use them as prizes.
For adults, certainly making a Christmas card as more of a craft item is good fun. You could make a wreath. You could just sing some Christmas songs. If you have the means, making cookies or even just decorating cookies can be a good activity. Cooking is an everyday event that is often skipped in most classes, but shopping for the materials, reading a recipe, and the actions involved with preparation provide a lot of exposure to language growth.