Near the end of Scene 8, Galy Gay sings the refrain "O Moon of Alabama," which comes from “Alabama Song” by Brecht and composer Kurt Weill, made famous in the opera The Rise and Fall of the City of Mahagonny (1930).
The opera is set in Wild West America, and characters include Alaskan Lumberjacks and an enterprising fugitive from justice named Leocadia Begbick. A whore named Jenny Smith sings “Alabama Song” as she leaves home to pursue "whiskey, dollars and pretty boys." You can hear Teresa Stratas sing the operatic version in this clip from a 1978 Metropolitan Opera production.
This article from Opera News contains an excellent analysis of the song, the opera, and the subversive impact of the Brecht-Weill musical style.