This is Peppermeloni. (seriously just look at that sexy motherf*cker). It's scientific name is Tumblrous Pepperonus.
The only known specimen is in a pot in David Karps treasure dungeon. It is a tradition that a single slice is given to every tumblr blog that reaches 500,000 followers.
It has the remarkable property of being as healthy as watermelon but tasting like cheesy pepperoni pizza.