Green’s Dictionary of Slang

butter-and-egg man n.

also butter-and-egger, butter and egg salesman, butter and milk man
[the dairy products such men often sold. The term was popularized by the nightclub owner Marie Louise ‘Texas’ Guinan (1884–1933), otherwise celebrated for her invariable greeting, ‘Hello sucker!’ Columnist Walter Winchell attributed the term to master of ceremonies Harry Richman, while the original ‘butter-and-egg man’ was supposedly ‘Uncle Sam’ Balcon, a New York provisioner. The term was further popularized first by Louis Armstrong’s song ‘The Butter-and-Egg Man’ (1924) and George S. Kaufman’s similarly named play of 1925]

1. [1920s–60s] (US) a prosperous farmer or small-town leading citizen who comes to the big city and poses embarrassingly as a playboy.

2. in attrib. use of sense 1.