Josh Gad, in his recently released memoir In Gad We Trust: A Tell-Some, opens up about a surprising conversation with his Love & Other Drugs co-star, Jake Gyllenhaal, who warned him against taking on a role in The Book of Mormon, the controversial musical-comedy from South Park creators Trey Parker and Matt Stone.

While juggling his work on The Daily Show and filming Love & Other Drugs in Pittsburgh, Gad played a demo of the musical for Gyllenhaal in the car. “I asked him if I should pursue the project further,” Gad recalled, “and he agreed to listen.” However, what began as a playful listen of the opening number “Hello!” took a drastic turn as the musical’s other tracks played.

As the music grew edgier, Gad recalls Gyllenhaal’s reaction shifting from joy to concern. “I skipped to another track, and his face slowly went from joyful enthusiasm to abject fear and terror,” Gad wrote. “He stopped the car and said, ‘Dude, you cannot do whatever this is. This will be way too controversial.’”

Gyllenhaal was shocked to learn that The Book of Mormon had been created by the same minds behind South Park. “Who the hell wrote this anyway?” he asked, to which Gad revealed the infamous creators: Trey Parker and Matt Stone. Despite Gyllenhaal’s warning, Gad went on to star as Elder Cunningham in the Broadway production, earning a Tony nomination for Best Actor during his 15-month run.