Simon was born on July 4, 1927, in the Bronx, New York. His father, Irving, worked as a garment salesman. Irving Simon's job forced him to leave his family periodically during Simon's childhood. Simon's mother, Mamie, was forced to work during these periods in such places as Gimbel's department store to support Simon and his elder brother Danny. After his parents divorced, Simon lived for a time in Forest Hills, New York, with relatives. From an early age, Simon displayed comic and writing talents, and his elder brother encouraged his efforts.

After graduating from high school in 1944, Simon attended several colleges, served in the Army, and taught himself to write comedy from books and imitating successful comics. After being discharged from the military in 1946, Simon was hired to work in the mailroom at Warner Brothers studios. Danny Simon already worked in the publicity department there. The brothers Simon...