It's one of a baker's dozen of pop-culture patterns for pumpkins this year. HalloweenCostumes.com puts them out annually as part of a big promotion for the biggest month on its calendar.
The gray area is where the orange rind is peeled off but the shell is left intact. White is left untouched. Black is a full cut through the rind, which in this case deepens the spoooooky spoooooky glare of Luigi's death-filled eyeballs. The full-sized pattern is here.
Other patterns include the Doctor Who Tardis (which looks incredibly complicated), Rocket and Groot from Guardians of the Galaxy (ditto — in fact most people would probably ask who that is supposed to be) and even Nicki Minaj from her "Anaconda" music video. Please don't carve a Nicki Minaj pumpkin. Your homeowner's association thanks you.