“Mom, when I grow up, I’d like to be a musician” (joke)

A popular music joke is:
 
Son: “Mom, when I grow up, I’d like to be a musician.”
Mother: “You can’t do both.”
 
The joke has been cited in print since at least 1996. In 1997, the joke was attributed to fiddle player Johnny Gimble (born in 1926) and his mother.
 
The joke has been told about specific musicians (such as guitarists and drummers) and also about non-musicians (such as actors, poets and members of a particular political party). The joke has also been told with a father (instead of a mother) giving the punchline.
 
   
Geocities
Trumpet Jokes
Last Updated December 11, 1996 by the webmaster.
(...)
What did little Johnny’s mother tell him when he said “I want to be a trumpet player when I grow up?”
“But Johnny, you can’t do both.”
   
Texas Monthly
My Willie
WILLIE NELSON AND I HAVE BEEN FREQUENTLY, SECRETLY FOND OF EACH OTHER FOR YEARS, BUT I’VE NEVER WRITTEN ABOUT HIM—UNTIL NOW.
by KINKY FRIEDMAN
SEPTEMBER 1997
(...)
Probably it has to do with what Johnny Gimble, the great country fiddle player, told me once aboard the Honeysuckle Rose. He said that when he was a kid he’d told his mother, “Mama, when I grow up, I’m gonna be a musician.” His mother had answered, “Make up your mind, son, because you can’t do both.”
 
Google Books
In a Silent Way:
A Portrait of Joe Zawinul
By Brian Glasser
London: Scantuary Publ.
2001
Pg. 275:
English jazz musician-cum-club-owner Ronnie Scott used to tell the story of a young man who went to his father and said, “Dad, when l grow up. l want to be a drummer.” and the tathei replied, “Well, make up your mind, son. You can’t do both.”
 
Google Books
22 December 2001, Billboard, “Words & Music” by Jim Bessman, pg. 34, col. 5:
Future country fiddler great Johnny Gimble’s mother’s admonition after him telling her, “Mama, when I grow up, I’m gonna be a musician”: “Make up your mind, son, because you can’t do both.”
 
Google Books
The Best Musicians’ Jokes
By Bruno Kassel and Carlo May
Pacific, MO: Mel Bay Publications, Inc.
2005
Pg. 45:
“Mom, when I grow up, I want to be a drummer.”
His mother scoffs and replies…
“Well, you can’t do both.”
 
Google Books
Cowboy Logic:
The Wit and Wisdom of Kinky Friedman (and Some of His Friends)
By Kinky Friedman
New York, NY: St. Martin’s Press
2006
Pg. 51:
“Mama, when I grow up, I’m gonna be a musician.”
“Make up your mind, son, because you can’t do both.” — LEGENDARY FIDDLE PLAYER JOHNNY GIMBLE AND HIS MOTHER
 
Twitter
Freema Agyeman
‏@FreemaOfficial
A fun Industry gag I heard today:
Kid says to Dad “I wanna be an actor when I grow up.” Dad says “you can’t do both.”
1:12 PM - 28 Apr 2014
 
Twitter
Dima Safieddine
‏@dimasafieddine
“I said, ‘Dad, when I grow up, I want to be a poet,’ and he said, ‘Well, you can’t do both.’”
3:33 PM - 15 Jun 2014
 
Twitter
GodlessLiberals.com
‏@GodlessLiberals
Son: Mom, when I grow up I’m gonna be a #Republican!
Mom: Well son, which is it? You can’t do BOTH!  #UniteBlue pic.twitter.com/1yYtg1RTps
11:15 AM - 27 Jun 2014