A popular riddle about the viola is:
 
Q: How do you keep a violin from getting stolen?
A: Put it in a viola case.
 
In other words, no one would steal a viola. THe joke has been cited in print since at least 1992.
   
 
Google Groups: rec.music.classical
lists
Gabe M Wiener
2/16/92
(...)
Q:  How do you keep your violin from getting stolen?
A:  Put it in a viola case.
 
Google Groups: rec.music.classical
Needed: Viola jokes
Liat Kaplan
4/2/94
(...)
How do you keep a violin from being stolen?
Put it in a viola case.
 
Google Groups: rec.humor
VIOLA JOKES
Fil Feit
10/6/94
(...)
Q: How do you keep your violin from getting stolen?
A: Put it in a viola case.
 
Google Books
The Musician’s Joke Book:
Knowing the Score
By Nancy J. Groce
London: Schirmer Trade Books
1996
Pg. ?:
How do you keep your violin from getting stolen?
Put it in a viola case.
     
Google Groups: alt.tasteless.jokes
How do you keep your violin from getting stolen?
Silver Surfer
8/10/98
Q: How do you keep your violin from getting stolen?
A: Put it in a viola case.
 
Google Books
Paroles à rire
By Eliane Daphy
Publications langues’O.
1999
Pg. 144:
Other jokes draw comparisons with other, more highly regarded instruments:
 
How do you keep your violin from being stolen? Put it in a viola case.
 
Google Books
The Musician’s Joke Book
By Jim Green
London: Wise Publications
2010
Pg. ?:
Q: How do you keep a violin from getting stolen?
A: Put it in a viola case.
   
Twitter
Jamie Palmatier
‏@jdpalmatier1016
@cchurko how do you keep a violin from being stolen? - Put it in a viola case 😉
2:29 PM - 8 Jul 2010
     
Twitter
Sandy Stevenson
‏@tourscotland
How do you keep a violin from getting stolen in Scotland ?  Put it in a bagpipe case.
5:45 PM - 28 Sep 2010
 
Reddit—Jokes
How do you keep a violin from getting stolen?
submitted January 8, 2017 by SluffAndRuff
Put it in a viola case.