The film was written by Farrelly and co-screenwriters of "Green Book" Brian Currie and Pete Jones ("Hey Heoka"), adapted from the documentary "The Greatest Beer Run Ever: A Story of Friendship Stronger Than War", which tells the true story of John "Chickie" Donohue: In 1967 during the Vietnam War, Donohue, a 26-year-old former U.S. Marine Corps member, set out from New York to Vietnam to find three childhood friends who were serving in the army and bring them beer.