So, lets say IF nopony in Equestria celebrates much of a "Thanksgiving", other than the Apples (and their relatives Oranges)... A very special, important, valuable (oh they're all the same thing) day, where the family gathers around to celebrate the history that had them on this very Sweet Apple Acres. Aka, the Apple Fest.
Applejack, after a day of preparing for the feast coming up, goes to have a simple chat with Big Mac. Just turns out to be more than that...