Fehn was born and raised in Des Moines, Iowa. Prior to joining Slipknot, he played as a kicker on the Wayne State University Football team. Fehn joined the band around April 1997, replacing percussionist Greg Welts, who was forced out of Slipknot after the band due to personal conflicts with drummer Joey Jordison which stemmed from Welts dating Jordison´s sister.
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 humour to the band." and that they "definitely need that guy." Prior to joining Slipknot in 1997, 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 custom 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.
In the early years of Slipknot before their signing with Roadrunner Records, Fehn was an electrician. In a recent interview with Face Culture, Fehn said that the band members gave him a hard time in his early years with the band. He described that his time during the self-titled album era was his "hazing period" with the band.
His mask was featured in the movie Harold and Kumar Escape from Guantanamo Bay.