“What is a relative minor?”/“A country western musician’s girlfriend.”

A popular musician joke about the relative keys is:
 
Q: What is a relative minor?
A: A country western musician’s girlfriend.
 
An Internet list circulated by at least 1995 was titled “Musical Terms Commonly Misunderstood by Country-Western Musicians, With Their Translated ‘Country’ Definitions.” Two definitions were:
 
Relative Major—An uncle in the Marine Corps
Relative Minor—A girlfriend
   
   
Wikipedia: Relative keys
In music, relative keys are the major and minor scales that have the same key signatures. A pair of major and minor scales sharing the same key signature are said to be in a relative relationship. The relative minor of a particular major key, or the relative major of a minor key, is the key which has the same key signature but a different tonic; this is as opposed to parallel minor or major, which shares the same tonic. Relative keys are closely related keys, the keys between which most modulations occur, in that they differ by no more than one accidental (none in the case of relative keys).
         
Google Groups: rec.music.classical
Musician Jokes
Bolen
3/18/95
(...)
Musical Terms Commonly Misunderstood by Country-Western Musicians, With Their Translated “Country” Definitions
——————————————————————————————————————
Diminished Fifth—An empty bottle of Jack Daniels
Perfect Fifth—A full bottle of Jack Daniels
Ritard—There’s one in every family
Relative Major—An uncle in the Marine Corps
Relative Minor—A girlfriend
 
Google Groups: bit.listserv.bgrass-l
Music Theory for Hillbilly Musicians (Long)
.(JavaScript must be enabled to view this email address)
11/7/96
A new friend sent me this “Internet Yuk,” and I just HAD to pass it on!
—Dan
Musical Terms Commonly Misunderstood by Country-Western Musicians, With Their Translated “Country” Definitions
Diminished Fifth—An empty bottle of Jack Daniels
Perfect Fifth—A full bottle of Jack Daniels
Ritard—There’s one in every family
Relative Major—An uncle in the Marine Corps
Relative Minor—A girlfriend

Google Groups: alt.humor
Music & Musicians
Keith E. Sullivan
1/14/98
(...)
MUSICAL TERMS AND BARS
Diminished Fifth—An empty bottle of Jack Daniel’s
Perfect Fifth—A full bottle of Jack Daniel’s
Ritard—There is one in every family
Relative Major—An uncle in the Marine Corps
Relative Minor—A girlfriend in West Virginia
 
Google Groups: microsoft.public.games.zone.fighterace
Musician Jokes . . . .
BBQ_Wabbit
11/14/00
(...)
Relative minor: A guitarist’s girlfriend.
 
Twitter
Bob Kostic
‏@causticbob
#redneckmusicalterms Relative Minor: A girlfriend
7:07 PM - 29 Jul 2010
 
Twitter
Gene Dasher Jr
‏@genedasher
Musical terminology of the day: “Relative Minor” - a bluegrass guitarist’s girlfriend.
9:00 AM - 18 Dec 2012
 
musicianscontact.com
Date Published: 06/27/2015
Subject: Jokes only musicians understand
(...)
What is a relative minor? A country western musicians’ girlfriend.
 
Twitter
MusicianHumor
‏@JokesBoutMusic
relative minor: a girlfriend.
1:33 AM - 7 Feb 2016