Not sure how long this hack has been available but it's simple. Order a family meal such as a giant feast or cheap as chips meal. When it asks you, add two sides and add 4 pieces of chicken. Then go to checkout and edit the side choices if you wish. Then
remove the family meal from your cart and voila $12.90 for four pieces of chicken and two sides.
If buying these separately you'll spend a good $23 so it's a great saving.
https://youtu.be/RhMjtZtHWKQ