“Shoot pool with a rope” (an impossible task)

You can’t shoot pool with a rope, just as you can’t push a string and you can’t push spaghetti. The “shoot pool with a rope” line has become a popular remark about male impotence.
 
“My sex life is like shooting pool with a rope,” New York-based comedian and actor Rodney Dangerfield (1921-2004) said in 1982. “Sex after ninety is like trying to shoot pool with a rope. Even putting my cigar in its holder is a thrill,” New York-born comedian and actor George Burns (1896-1996) was credited with in 1990. It’s uncertain when both Dangerfield and Burns first used the “shoot pool with a rope” line. The Burns quote has been the more popular of the two.
 
 
Google News Archive
4 October 1982, The Gazette (Montreal, Quebec), “No respect but lots of laughs for master comic Dangerfield” by Mike Boone, pg. D-7, col. 2:
Dangerfield pokes fun at his age (...) and, most hilariously, his ineptitude as a lover: “My sex life is like shooting pool with a rope.”
   
Google Books
The Fourth—and by Far the Most Recent—637 Best Things Anybody Ever Said
By Robert Byrne
New York, NY: Atheneum
1990
Pg. ?:
175
Sex after ninety is like trying to shoot pool with a rope. Even putting my cigar in its holder is a thrill.
George Burns
 
Urban Dictionary
shooting pool with a rope
trying to have sex without an erection
I drank 16 beers and took her back to my place and it was like shooting pool with a rope.
by brighton71 October 05, 2007
 
Urban Dictionary
Shoot pool with a rope
when one’s dick cannot become hard during sex due to the amount of alcohol (i.e. whiskey) consumed. a.k.a. “whiskey dick.”
Because of my heavy drinking habits i often shoot pool with a rope when I’m with my slampiece, but its no problem because i always hammer it out in the morning.
by big dh February 11, 2011
 
YouTube
How to shoot pool with a rope
Jeff Hudson
Published on Dec 21, 2014
How to shoot pool with a rope
 
Twitter
Jewish Comedians
‏@JewishComedians
George Burns: Sex at age ninety is like trying to shoot pool with a rope. | #Quotes
7:23 PM - 22 Nov 2015