Watt was recruited to play "fuzz bass, fills and solos (and) just making things fatter" on the album, Gigwise.com reported Monday.
Watt was the founding bassist form The Minutemen and is playing with the reunited Iggy and the Stooges.
"I ended up playing on six of the songs. I had no idea what it was going to be like, but it ended up being pretty interesting," Watt told Gigwise.com. "I heard that Kelly won some game show but I was really impressed how she sang her ass off."
"It was intense. I'm really glad I had the experience -- it was trippy and everyone gave me much respect," he said.