The marshmallow paste goes on one slice of bread. Peanut butter goes on the other. United, they form the fluffernutter sandwich. It’s unique to Boston (US) and its surrounds, and I have absolutely no idea why it has not yet conquered the world.
Actually, it could be that Fluff Boy’s empty, soulless eyes and sinister grin come from the same nightmare dimension as all clowns, and will terrify anybody under the age of nine.
But when you get past that, Fluff is awesome.