“What do you get when you drop a piano on an army base?” (joke)

A popular piano riddle is:
 
Q: What do you get when you drop a piano on an army base?
A: A flat major.
 
The joke has been cited in print since at least 1977.
 
“What do you get when you drop a piano down a mine shaft?”/“A flat minor” and “What do you get if you drop a piano on a child?”/“A flat minor”  are related jokes.
         
   
Newspapers.com
24 January 1977, Minneapolis (MN) Tribune, “Mad Jack and Black Label Bunch, Space Bop Orchestra entertain” by Michael Anthony, pg. 7B, cols. 3-4:
“Hey,” says mandolin player Bob Douglas, “You know what you get when you drop a piano on a military base, dontcha?” “No,” says fiddler-guitarist “Pop” Wagner. “Whaddaya get?” “A-flat Major,” says Douglas. The joke goes over well, the punch line repeated around the room.
 
Google Books
Bass World: The Journal of the International Society of Bassists
Volumes 21-22
1996
Pg. 73:
Q: What do you get when you drop a piano down a mine shaft?
A: A flat minor.
 
Q: What do you get when you drop a piano on an army base?
A: A flat major.
 
Old Fulton NY Post Cards
25/26 July 1998, Rogersville (TN) Review, “Website offers musical humor,” pg. 3A, col. 4:
What do you get when you drop a piano down a mine shaft? A flat minor.
What do you get when you drop a piano on an army base? A flat major.
     
Google Groups: alt.humor
Musical Humour - Keyboards
Desiato
12/16/99
(...)
What do you get when you drop a piano down a mine shaft? A flat minor.
 
What do you get when you drop a piano on an Army base? A flat Major.
 
Google Books
Guide to College Majors:
Everything You Need to Know to Choose the Right Major
By Princeton Review (Firm)
New York, NY: Random House
2005
Pg. 533:
A Joke
What do you get when you drop a piano on an army base? A flat major.
 
Google Books
Best Ever Classroom Jokes:
Because some of us never grow up
By Mike Haskins
Pavilion Books
2015
Pg. ?:
What do you get if you drop a piano on an army base?
A flat major.
 
What do you get when you throw a piano down a mine shaft?
A flat miner.
 
Twitter
John Brookfield
‏@MeltHell
What do you get when you drop a piano on an army base? A flat major. http://jokes4all.net/joke_5.html?utm_source=dlvr.it&utm_medium=twitter … #jokes
3:10 AM - 19 Oct 2015