Everybody loves Christmas songs, but as teachers we also prize mental stimulation. This activity has the names of many popular Christmas songs written verbosely; the goal is to figure out the original titles. This is a great activity to do on the last day before winter break. (After doing this with my students, some of them learned that they don't know as many Christmas songs as they thought they did, and others learned that they know a lot of Christmas songs but only remember them after hearing the answers.
My favorite part is reading through the answers in the last few minutes of the period and hearing them shout out things like, "Of COURSE that's the answer! I should've known!") This works best in a roughly 60-minute period, though you could make it into a competition and let students work in groups if your class periods are shorter.
I do not want digital copies of my work floating around the internet. Please keep all electronic copies for your eyes only, and don't hand out the answer key.