Looking at my local Papa John's, a large 1-topping pizza is regularly $14.50 so you can get two large, 1-topping pizzas for $7.25 each under the deal (compared to an ongoing deal they have in my area where you can get a large, 1-topping pizza from Papa John's for $8.99).
The BOGO promotion runs through January Wednesday, 28, 2015.
