He also wrote or co-wrote the movies Bruce Almighty, Click, A Night at the Roxbury, and Superstar.
As a Rockefeller Center tour guide, Koren would hand jokes to David Letterman and Dennis Miller as they passed in the hall, which landed him a writing gig on SNL.
In addition, he helped write and performed on Adam Sandler’s Platinum debut album They’re All Gonna Laugh at You.
Later, he became a writer for Seinfeld, and wrote the episodes "The Abstinence", "The English Patient", "The Serenity Now", and "The Dealership".
[citation needed] Koren has executive-produced several films such as Adam Sandler's Grown Ups (2010), Just Go with It (2011), Blended (2014), and Pixels (2015).