Shall We Dance is the seventh of the ten Astaire-Rogers musical comedy films. It was released in 1937. The idea for this film originated in the studio's desire to exploit the successful formula created by Richard Rodgers and Lorenz Hart with their 1936 Broadway hit On Your Toes, which featured an American dancer getting involved with a touring Russian ballet company, and which featured the famous "Slaughter On Tenth Avenue" satirical ballet created by the Russian émigré choreographer George Balanchine. In a major coup for RKO, Pan Berman managed to attract the Gershwins (George Gershwin wrote the symphonic underscore and Ira Gershwin the lyrics) to score this, their second Hollywood musical (their first had been Delicious). Wikipedia
Newsboy: (shouting) Petrov and Keene: secret marriage!
Peter P. Peters: We're the only two people in New York who don't think we're married.
Linda Keene: Think? I know we're not.
Peter P. Peters: I'm beginning to have my doubts.