Just when you thought there weren't any more possible combinations of Slayer and Wham! left, YouTube mashup overlord Bill McClintock is here to put you in the Christmas spirit. It's "Last Christmas" by Wham!, except all the vocals are "South of Heaven" by Slayer. So it's a very specific type of Christmas.
Wham! and Slayer got mashed up for Christmas before, with "Last Christmas" getting mixed up with Slayer's Angel of Death. Here are three other excellent Slayer/Wham! mashups that are not Christmas related.