On WTF with Marc Maron, he explained that, after dropping his résumé off at the MTV offices in hopes of landing an internship, a Letterman staff member approached him outside the studio and asked if he’d like to sit in the audience because they needed seat fillers.
Inside, he told one of the pages, “This is my dream job. Who can I talk to to get this job?” So, the page brought over their boss, who said, “I’m sorry. I can’t help you unless you have a résumé.”
Ben said, “I took out all 20 résumés from my backpack, and he laughed, set up a meeting, and that’s how I got that job, which led to me writing jokes for Letterman’s monologue, which started the whole thing.”