A festival unlike any other, What the Fluff? (flufffestival.com) returns to Somerville’s Union Square September 21 from 3–7 p.m. Sporting the theme Fluff Travels: All Roads Lead to Fluff! for the 14th edition of the celebration of the invention of Marshmallow Fluff in the area in 1917, this year marks a slight change in the celebration’s footprint as ongoing construction has pushed the fun farther into the heart of Union Square. One thing that hasn’t changed, however, is the zany activities associated with What the Fluff?, including Fluff jousting, Fluff bowling, live music, appearances by the fabulous Flufferettes, a cooking contest and plenty of sweet and savory food options—all involving Marshmallow Fluff, naturally.