White guy: *rapping Eminem* Will Smith don't gotta cus in his raps to sell records; well I do so fluff him and fluff you to!
Friends: Dude wtf, did you just say fluff?
Maura: What is this white substance?
Jane: Fluff.
Maura: Light, downy particles of cotton?
Jane: It's marshmallow, and the brown substance is called peanut butter. It's ground up, heavy, oily particles of peanuts.
An abbreviation for "marshmallow fluff," a gooey white substance mainly used as a sandwich spread. Can also be used in place of marshmallows for baking purposes. Often made into a contraction with peanut butter as "fluffernutter," a combination of the two sandwich spreads on bread.