The "Free Cheeseburger, Mayo Chicken, or McFlurry" offer at McDonald's allows customers to enjoy a complimentary item with their purchase. Customers can choose between a free cheeseburger, mayo chicken sandwich, or McFlurry dessert, providing a delicious bonus to their order. This promotion entices individuals to visit McDonald's and indulge in their favorite menu items while receiving an additional treat at no extra cost. Whether it's a classic cheeseburger, a tasty chicken sandwich, or a delightful ice cream treat, this offer adds extra value and enjoyment to the McDonald's dining experience.