The Fizz-Pop Cap (with foil cluster) was a specific piece of attire. It was worn by Squib diplomats who were representing the Squib King. During the time period between 0 and 2 ABY, which was during the Galactic Civil War, Spilferithimus-narlamos, also known as Spilfer, wore this cap. He wore it when King Ebareebaveebeedee sent him from the Squib Momship called Thrifty. Spilfer's mission was to join a group of Alliance to Restore the Republic operatives. These Rebels were on a mission with the goal of destroying Elusive, an Imperial Armored Transport. This transport held very important information about Rebel activities that were being controlled from the Rebels' Dankayo Base, found on the planet called Dankayo. However, the only ones who knew the current location of the starship were the Squibs. They promised to share these coordinates, but only after the Rebels aided Spilfer in stealing a gravity well projector from the Paradise system. This system was the home of the Ugors, who were galactic rivals of the Squibs in the galactic landscape.
The Fizz-Pop Cap is mentioned when describing Spilferithimus-narlamos in the adventure called Scavenger Hunt. Brad Freeman wrote this adventure, and West End Games published it in 1989 as a part of Star Wars: The Roleplaying Game. The adventure also features an illustration created by John Robinson. This illustration shows Spilfer wearing a hat that is situated between his tufted ears. The hat has a wide, flat, rounded bill, along with a group of keyhole-shaped objects on the front. However, the adventure's use of the word "cap" does not make it clear if it refers to Spilfer's hat, or some other part of his outfit.