Though Benny Blanco has been in the news lately because of his relationship with Selena Gomez, the producer is a prolific hitmaker who has worked on countless top-charting tracks. In an interview with Howard Stern to promote his new cookbook, the 36-year-old musician talked about the origin of “I’m Batman,” a song he, Ed Sheeran, and Lil Dicky wrote for 2017’s The Lego Batman Movie.

“I never write songs for movies, but I really loved the first Lego Movie,” Blanco explained. “And we submitted this song, and it was all about Batman’s penis. The people wrote us back and they said, ‘You’re disgusting. This is childish. Please don’t ever send us any songs ever again. You should be ashamed of yourself.’”

“That’s always my thing. I’m like let’s write about a cock. That’s always my first idea,” he continued. “I remember we turned it in, they said it was dogshit, and then six months later we get a call, they say, ‘Hey, we actually like this, could you just change this line and this line?’ And then they came around.”

You can watch clips from the interview, where he also discusses Sia writing Rihanna’s “Diamonds” in fifteen minutes, below.