(Oxford English Dictionary)
white-shoe slang (chiefly U.S.), effeminate, immature;
1957 J. D. SALINGER Zooey in New Yorker 4 May 62/2 Phooey, I say, on all *white-shoe college boys who edit their campus literary magazines. Give me an honest con man any day. 1974 G. JENKINS Bridge of Magpies vi. 85 What sort of white-shoe captain are you? 1975 N.Y. Times 22 Sept. 33/1 Covert operations can be stripped from the CIA... So can such monkey business as dropping simulated poison cannisters in the New York subwaysthe games of white-shoe boys who never grew up.
September 1953, Esquire, pg. 59:
HOW SHOE CAN YOU GET?
America's premier student of snobs and brows peers through the ivied windows at hallowed precincts and their new social hierarchy of White Shoe, Brown Shoe, Black Shoe
by RUSSELL LYNES
At Yale there is a system for pigeonholing the members of the college community which is based on the word "shoe." Shoe bears some relation to the word chic, and when you say that a fellow is "terribly shoe" you mean that he is a crumb in the upper social crust of the college, though a more kindly metaphor might occur to you. You talk of a "shoe" fraternity or a "shoe" crowd, for example, but you can also describe a man's manner of dress as "shoe." The term derives, as you probably know, from the dirty white bucks which are the standard collegiate footwear (you can buy new ones already dirty in downtown New York to save you the embarrassment of looking as though you hadn't had them all your life), but the system of pigeonholing by footwear does not stop there. It encompasses the entire community under the terms White Shoe, Brown Shoe, and Black Shoe. (...)