“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” A different version is:
 
“A bar goes into a guy. It was a gay bar.”
 
The joke was posted on Reddit—Jokes on September 10, 2018. This version of the joke is, as might be expected, probably not safe for work.
 
“Stop me if you heard this one… a bar goes into a guy…” was posted on Twitter by Sam Grittner on April 4, 2009. “#Comedy A bar goes into a man. He dies immediately” was posted on Twitter by FrankCotolo on September 17, 2011.
   
       
Twitter
Sam Grittner
@SamGrittner
Stop me if you heard this one… a bar goes into a guy…
8:42 AM - 4 Apr 2009
     
Twitter
Victoria
@I__Victoria__I
So, a bar goes into a man….http://tinyurl.com/y8qymrh
I love when history is reinterpreted because of random internet stuff.
7:51 PM - 25 Jan 2010
   
Twitter
FrankCotolo
@FrankCotolo
Joke with no funny ending: A bar goes into a man ...
1:10 AM - 15 Jul 2011
   
Twitter
FrankCotolo
@FrankCotolo
#Comedy A bar goes into a man. He dies immediately.
4:56 PM - 17 Sep 2011
 
Twitter
Barking Unicorn
@BarkingUnicorn
Stop me if you’ve heard this one. A bar goes into a guy… http://yhoo.it/Nv4V94
3:43 PM - 17 Aug 2012
 
Reddit—Jokes
A bar goes into a guy
submitted September 10, 2018 by ExpressiveAnalGland
It was a gay bar.
 
Twitter
Best of Reddit
@BestoReddit
A bar goes into a guy : It was a gay bar.
1:56 AM - 11 Sep 2018
 
Twitter
Jokes OK Please
@jokesokplease
A bar goes into a guy. It was a gay bar. #joke
3:10 AM - 11 Sep 2018
 
Twitter
Alison Slam Duckery
@SlamRush
A bar goes into a guy It was a gay bar.
8:35 AM - 11 Sep 2018