I'd heard rumors from up north and decided to do a little online research on this one. Turns out you just get a grease covered picture of pie under your pie.
A new Winnipeg pizza place is delivering more than pepperoni with its pies.
Corey Wildeman has launched Porno Pizza, a delivery-only pizza business that places pornography where you would usually find only cardboard – under the pizza.
Not being all that impressed I'll direct you to the search I did. Note the first link (NSFW). Perhaps this explains why..
Written by Ogre"It's about 75 to 80 percent female that are placing the orders and are taking orders at the door," he said.

