“Don’t tell my mother I’m a banker—she thinks I play piano in a whorehouse”

“Don’t tell my mother I’m a banker—she thinks I play piano in a bordello/brothel/cat house/whorehouse” is a joke about how little people think of bankers. The joke began during the financial hard times of the Great Depression (about 1934).
 
The joke has involved many other professions and has been used mostly for politicians or lobbyists since the 1980s-1990s.
   
   
Google Books
International Affairs: journal of the Royal Institute of International Affairs
Volume 13
1934
Pg. 348:
Wilbur presses him, and he says, “Well, I have become President of a bank, but don’t tell my mother; she still thinks I am playing the piano in a house of ill fame.”
 
Google Books
The Jazz Record Book
By Charles Edward Smith, Frederic Ramsey, Charles Payne Rogers and Bill Russell
New York, NY: Smith & Durrell
1942
Pg. 12:
A large sporting house had a number of parlors, each with a piano. The quip: “Don’t tell my mother I’m a bond salesman; she thinks I’m making an honest living playing piano in a sporting house,” recalls the fact that there were good nights when top men such as Tony and Jelly Roll pocketed as much as a hundred dollars in tips.
 
Google News Archive
21 February 1942, Youngstown (OH) Vindicator, “The Banks Lend a Hand,” pg. 8, col. 1:
Not so long ago the story was going around about the young man who was asked what he was doing and replied: “Working in a bank. But don’t tell my mother; she thinks I’m playing piano in a jook joint.” That was at the height of the banks’ unpopularity because of their forced closing.
 
10 October 1947, Wisconsin State Journal (Madison, WI), pg. 6, col. 1:
Break the News to Mother
It wasn’t very many years ago that a sign-of-the-tough-times joke went something like this:
 
“Don’t tell my mother I’m a banker. She thinks I play piano in a saloon.”
 
Google Books
A Different Face
By Olivia Manning
New York, NY: Abelard-Schuman
1957
Pg. 96:
There was the standard story about the young man who wrote home: ‘Please don’t tell my mother I’ve joined the P.I. She thinks I play a piano in a brothel.’
 
26 July 1964, Lake Charles (LA) American Press, pg. 4, col. 3 editorial cartoon:
(A man in a newsroom to an angry member of the public—ed.)
“Please Don’t Tell My Mother Where I Work! She Thinks I Play Piano in a House of Ill-Repute!!”
     
Google Books
The Great Slump:
Capitalism in crisis, 1929-1933

By Goronwy Rees
New York, NY: Harper & Row
1971, ©1970
Pg. 60:
Chief among them, perhaps, should be counted the bankers, who almost overnight lost their reputation, not merely for prudence and sagacity, but even for honesty; a popular music-hall joke of the depression was: ‘Don’t tell my mother I’m a banker, she thinks I play the piano in a brothel.’
 
Google Books
The Political Economics of International Bank Lending
By David Gisselquist
New York, NY: Praeger
1981
Pg. 73:
Don’t tell my mother I’m a banker, she thinks I play the piano in a brothel.
Depression joke
     
Google Books
Private Eye
Issues 497-522
1981
Pg. 53:
(All politicians are liars. Or the American crack: Don’t tell my mother I’m a politician. She thinks I play the piano in a whorehouse).
 
Google Books
How to Get the Best Advertising from Your Agency:
How it works, how to work with it—a management primer for advertisers

By Nancy L. Salz
Englewood Cliffs, NJ: Prentice-Hall
1983
Pg. 2:
Jock Elliott, former chairman of Ogilvy & Mather International, often quotes the old saw: “Don’t tell my mother I work in advertising; she thinks I play piano in a whorehouse.”
 
Google Books
Night of the Fox
By Jack Higgins
New York, NY: Simon & Schuster (Pocket Books)
1986
Pg. 168:
“I loathe politics. It reminds me of the senator in Rome who’s supposed to have said: ‘Don’t tell my mother I’m in politics. She thinks I play the piano in a brothel.’”
 
Google News Archive
30 June 1990, Florence (AL) TimesDaily, “Ex-politicians find ‘revolving door’ profitable” by Philip Rawls (Associated Press), pg. 6A, col. 2:
MONTGOMERY—A sign on Mike Weeks office wall says: “Don’t tell my mother I’m a lobbyist. She thinks I play piano in a whorehouse.”
     
Google Books
Honest Government:
An ethics guide for public service

By W. J .Michael Cody and Richardson R. Lynn
Westport, CT: Praeger
1992
Pg. 1:
Americans have always had a healthy skepticism about politicians, reflected in an old saying: “Don’t tell my mother I’m a politician. She thinks I play piano in a whorehouse.”
 
The Independent
Column One: Politicians? Some of them are almost human
Sean O’Grady and Paul Grey
Tuesday, 23 November 1999
DON’T TELL my mother I’m a politician, she thinks I play the piano in a brothel.” So runs the old joke.
       
Google Books
Encarta Book of Quotations
By Bill Swainson
New York, NY: St. Martin’s Press
2000
Pg. 27 (ANONYMOUS):
Don’t tell my mother I’m in politics — she thinks I play the piano in a whorehouse.
U.S. saying
 
Google Books
Crazies to the Left of Me, Wimps to the Right:
How One Side Lost Its Mind and the Other Lost Its Nerve

By Bernard Goldberg
New York, NY: HarperCollins
2008, ©2007
Pg. 146:
In fact, there’s an old joke that pretty much sums up the character of these “profiles in courage” and the “high esteem” in which they’re held:
 
“Don’t tell my mother I’m in politics. She thinks I play the piano in a whorehouse.”