Stock brokers and finances might not sound like a particularly festive film plot, but Dan Aykroyd and Eddie Murphy really pull it out of the bag in Trading Places. Aykroyd even dresses up as Santa to gatecrash his office holiday party. (Office parties are an ever-common theme in Christmas films.) If you've never seen this film, get the mince pies out and whizz it straight to the top of your must-watch list.