1. Posehn began with guest appearances and mainly small roles in TV shows.
2. He was on 28 episodes of Mr. Show with Bob and David , a sketch comedy series on HBO.
3. In the Seinfeld episode “The Burning” , he played a patient, when Kramer “was given” gonorrhea.
4. His character was instructed to “act out” to a group of medical students how a surgeon left a sponge in him post surgery.
5. Posehn also wrote the Space Ghost: Coast to Coast episode “Cahill” with Ben Karlin.
6. He played the voice of Jim in Mission Hill on the WB .
7. On an Adult Swim production, Aqua Teen Hunger Force, he voiced the Wisdom Cube in the 2003 episode “The Cubing”.
8. He also appeared in the 2005 pilot for The Showbiz Show with David Spade, in a segment called “The Nerd Perspective”, in which he gave a scathing criticism of MTV and its declining quality.
9. He was featured on the 2005 documentary series The Comedians of Comedy on Comedy Central and Showtime.
10. He co-stars on The Sarah Silverman Program with Steve Agee as a gay couple who is friends with Silverman, and also wrote the season three finale “Wowschwitz”.
11. In 2007 he joined the first season of the MTV sketch comedy series Human Giant, as a writer and performer, and voices Glen Furlblam, the biggest fan of Dr. Two-Brains on the PBS Kids animated series WordGirl.
12. He also voiced the character Hayashi in the English dub of Pom Poko.
13. He participated in the Comedy Lineup of the 2008 Bonnaroo Music and Arts Festival, which included Louis C.K., Janeane Garofalo and Zach Galifianakis.
14. During his 2008 routine on Comedy Central Presents he referred to his Wikipedia article, which he supposedly vandalized. In 2010, Posehn released his second album Fart and Wiener Jokes.
15. In 2011, Posehn agreed to perform at the Gathering of the Juggalos.
16. Some of his fans criticized this decision as being “not metal”. In 2013, Posen released his third comedy album and first DVD, The Fartist.