Gustav Gerson Kahn was an American lyricist who contributed a number of songs to the Great American Songbook, including "Pretty Baby", "Ain't We Got Fun?", "Carolina in the Morning", "Toot, Toot, Tootsie ", "My Buddy" "I'll See You in My Dreams", "It Had to Be You", "Yes Sir, That's My Baby", "Love Me or Leave Me", "Makin' Whoopee", "My Baby Just Cares for Me", "I'm Through with Love", "Dream a Little Dream of Me" and "You Stepped Out of a Dream".

"Ain't We Got Fun" is a popular foxtrot published in 1921 with music by Richard A. Whiting, lyrics by Raymond B. Egan and Gus Kahn.