Wiktionary
tell it to sweeney
phr. (context idiomatic dated English) I do not believe what you said.
Wikipedia
Tell It to Sweeney
Tell It to Sweeney is a 1927 American comedy silent film directed by Gregory La Cava and written by Monte Brice, Kerry Clarke, George Marion Jr. and Percy Heath. The film stars Chester Conklin, George Bancroft, Jack Luden, Doris Hill, Frank Bond and William H. Tooker. The film was released on September 24, 1927, by Paramount Pictures.