As well as lending his percussion talents to the band, Fehn has also sung backing vocals on a number of songs Slipknot has both recorded and performed live. Outside Slipknot, Fehn is a very keen golfer, and evidences this on the band’s 2006 DVD, Voliminal: Inside the Nine, where he is interviewed while playing golf. Fehn describes himself as a “big fan of the band” and says of Slipknot, “the world needed something like this.” Slipknot bassist Paul Gray stated in an interview that Fehn “often brings humor to the band.” and that they “definitely need that guy.” Fehn would wear a Pinocchio-style mask and would frequently stroke the nose as if he was masturbating. Prior to joining Slipknot in 1998, Fehn was close friends with Slipknot’s percussionist Shawn Crahan. According to Fehn, he had originally asked Crahan if he could be drummer Joey Jordison’s drum tech. Shortly after his request was made, Fehn was given an offer to play percussion in the band. Fehn was then given a rough demo that contained all of Slipknot’s songs. Fehn has said that “Spit It Out” was the song that stood out to him the most. Fehn then tried out on percussion and was subsequently made part of Slipknot. Of the nine members, Fehn was the eighth to join the band.

On March 14, 2019, Fehn filed a lawsuit against the band citing payment being held back. Fehn specifically accused Corey Taylor and Shawn Crahan for what he felt was questionable business dealings.

On March 18, 2019, Fehn officially split with Slipknot following his lawsuit. However, a few days later, the message was removed from the website and according to Fehn’s lawyer, the percussionist’s employment status with the band had not changed since his initial filing.