These are the novelty Pizza Playing Cards manufactured by GAMAGO and available through Spilsbury ($10, also available in donut form complete with hole -- pic below). They come in a pizza box, are slice shaped, and have an image of a pizza on the back. Will they be easy to mark so you can cheat? Yes. But what's the fun in cheating? Oh, shucks, looks like I lost again! *unbuckling belt* "This is go fish, not strip poker." Man, I remember when game nights used to be fun.
Keep going for a shot of the donuts.
Thanks to Ashley I, who agrees plus the other players can't fault you for eating a few cards if you lose.