If you put a cigarette in someone's eye, the eye swells up similar to the way a marshmallow expands when it's heated.
person 1: "eeww i saw you and your girlfriend kiss yesterday!"
person 2: "oh, shut up, you marshmallow."
person 1: "OMG that guy in the movie just chopped off that guy's head!!!"
person 2: "stop being such a marshmallow; it's just a movie."
i hope i turn into one someday so i can eat myself...