Joh Yowza was a male Yuzzum performer for the Max Rebo Band. Yowza joined the original band members Maximilian Rebo, Sy Snootles, and Droopy McCool, who had already been performing together for years. He often performed duets with Snootles, who was the lead vocalist. Rebo regarded Yowza as irksome and did not like how he seemed to hog the spotlight. Yowza was also known to have his own compositions that he liked to introduce in spite of the band's prepared material, which Rebo also did not appreciate.
Shortly before the Battle of Endor, Yowza and the rest of the band performed at Jabba the Hutt's palace on the planet Tatooine. The performance came to a halt when Jabba dropped his slave dancer Oola into the rancor pit, as Yowza gasped in horror. Among Jabba's courtiers, there were many people who disliked Yowza's voice and dreamed of silencing him brutally. The Hutt, however, appeared to like the Yuzzum singer, and Jabba's opinion was the only one that mattered in his palace. At some point, Yowza left the band and was to do a solo concert at Oga's Cantina on Batuu a few rotations after the skirmish at Kat Saka's farm.