To take advantage of the offer, you have to place an order online totaling $15 or more and enter the promo code "PLAYMAKER" on or before Sunday, September 14, 2014.
The day after the order, 25 Bonus Papa Points will be deposited in your Papa Rewards account, which is enough to redeem for a free large, 3-topping on your next order. You'll need to use the points before Sunday, September 28, 2014 though, as that's when they expire.
You can find further details on the deal at: http://www.papajohns.com/playmaker/.