As well as contributing to its books and articles, he has written and starred in original videos for the comedy website—appearing in series such as Hardly Working and Very Mary-Kate—and was a cast member on its short-lived MTV program The CollegeHumor Show.

Blumenfeld was born in Afula, Israel,[3] and moved to Los Angeles at the age of two[4] with his parents and two older brothers—his family is Reform Jewish.

[7] Blumenfeld graduated from the Haas School of Business at the University of California, Berkeley with a Bachelor of Science degree, hoping to get a creative job in advertising or marketing while writing comedy on the side.

[9] He is a basketball fan, and supports the Los Angeles Lakers—his favorite players are Nick Van Exel and the late Kobe Bryant.

After seven videos were posted over two years, there was an 18-month hiatus culminating in Seidell tricking Blumenfeld into thinking he had won USD$500,000 after taking a blindfolded half-court basketball shot.

[14] The pranks have led to Seidell and Blumenfeld being interviewed by Wired magazine[14] and appearing on Jimmy Kimmel Live!.

[16] The staff members wrote, filmed and starred in the show, which is set in the CollegeHumor offices and has a scripted reality premise.

[22][23] The Michigan Daily's Eric Chiu said "Hosts Blumenfeld and Seidell do what they can with their material, but their banter and commentary is mostly forgettable", and "the Prank War series on CollegeHumor.com is a perfect example of discomforting gags done right ...

"[22] In the July 19, 2017 episode of Blumenfeld and Hurwitz's podcast If I Were You for which Seidell was the guest, the two founders of Prank War publicly confirmed that the series was staged.

[9] Their first video was called "Quick Characters": it was unscripted, and involved either Hurwitz or Blumenfeld spontaneously pointing a camera at the other and instructing them to act in a certain way.

[1] Blumenfeld received a nomination for the 2013 Streamy Awards for Best Male Performance: Comedy because of his role in Jake and Amir.

[28] On May 13, 2013, Blumenfeld and Hurwitz announced their first new project since Jake and Amir: a comedy audio podcast called If I Were You, in which they give advice to listeners who submit questions.

[33] Blumenfeld starred in the 2009 short film The Old Man and the Seymour alongside colleagues Streeter Seidell and Dan Gurewitch, as well as Shawn Harrison, Liz Cackowski and Jordan Carlos.

Better With Popcorn's George Prax said that he played "the 'unfunny' guy who actually ends up coming off as the funniest of all to the audience", and that Blumenfeld "should be guesting and starring in many more things".

[37] Reviews largely did not remark on his performance,[38][39][40][41][42] although IGN's Eric Goldman said "there isn't much to the Todd and Adrian scenes",[37] and Pajiba's Daniel Carlson thought the scriptwriters treated the characters as "living props".

commended the film's "strong supporting cast", saying that Lennon and Blumenfeld "provid[ed] constant amusement".