A popular fiddle/violin joke among musicians is:
 
Q: What’s the difference between a violin and a fiddle?
A: No one minds if you spill beer on a fiddle.
 
The joke has been cited in print since at least 2005 and is of unknown authorship.
 
 
Google Groups: rec.music.makers.bowed-strings
violin, cello, bass, other jokes
Charlie Way
6/8/95
(...)
What’s the difference between a fiddle and a violin?
No-one minds if you spill beer on a fiddle.
 
Google Groups: rec.music.folk.tablature
dumb question..
kevin john wilhite
4/1/98
(...)
What’s the difference between a fiddle and a violin?
No-one minds if you spill beer on a fiddle.
 
Google Books
Alternative Strings:
The New Curriculum
By Julie Lyonn Lieberman
Pompton Plains, NJ: Amadeus Press
2004
Pg. 51:
What’s the difference between a violin and a fiddle?
No one minds if you spill beer on a fiddle.
 
Google Books
The Best Musicians’ Jokes
By Bruno Kassel and Carlo May
Pacific, MO: Mel Bay Publications, Inc.
2005
Pg. 28:
What’s the difference between a fiddle and a violin?
No one minds if you spill beer on a fiddle.
 
Google Books
The Musician’s Joke Book
By Jim Green
London: Omnibus Press
2010
Pg. ?:
Q: ...And another difference between a violin and a fiddle?
A: No one minds if you spill beer on a fiddle.
 
Daily Press (Newport News, VA)
Mark O’Connor on fiddles, violins and what Christmas means to him
By Mike Holtzclaw
DECEMBER 1, 2014, 9:17 AM
There’s an old joke among musicians that goes something like this: What is the difference between a fiddle and a violin? Answer: You don’t spill beer on a violin.
 
Twitter
Jordan keigher
‏@Jordan_keigher
The difference between a violin and a fiddle is that you don’t spill beer on the violin.
6:46 PM - 1 Dec 2014