“I tried to write a drinking song once, but I couldn’t get past the first bar”

A “bar” can mean a musical section, but it can also mean a place that serves drinks. A joke was published in the Chicago (IL) Daily Tribune on October 28, 1955:
 
“Uncle Helmer tried to write a drinking song, but he can’t get past the first bar.—Jasper Jr.”
   
       
28 October 1955, Chicago (IL) Daily Tribune, “In the Wake of the News” by David Condon, pt. 4, pg. 1, col. 2:
Help! Help!
Uncle Helmer tried to write a drinking song, but he can’t get past the first bar.—Jasper Jr.
   
19 July 1997, Times Union (Albany, NY), “Watch This Space” by Steve Barnes, pg. D1:
“My friend was going to write a drinking song, but he never got past the first bar.”
 
Google Groups: alt.fun.with.tob
Humor from the Net
Bill McCray
8/8/00
(...)
I tried to write a drinking song once, but I couldn’t get past the first bar.
 
Twitter
Roy Batty
@EyesofChew
RT @Fozziedog: I tried to write a drinking song once, but I couldn’t get past the first bar << good one! 😊

3:04 PM - 19 Nov 2009
     
Google Books
The Mammoth Book of One-Liners
Edited by Geoff Tibballs
London, UK: Constable & Robinson Ltd
2012
Pg. ?:
I tried to write a drinking song once, but I couldn’t get past the first bar.
 
Twitter
Mike Elliott
@ThatMikeElliott
I’m trying to write a drinking song but I can’t get past the first bar
6:28 AM - 17 Aug 2012
     
Twitter
John
@JFD1960
I tried to write a drinking song once. I couldn’t get past the first bar.
5:03 PM - 14 Aug 2017
 
Twitter
John
@JFD1960
I tried writing a drinking song once but didn’t get past the first bar
5:37 PM - 30 Apr 2018