“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” A circle version is:
   
“A square and a circle walk into a bar. The square says to the circle, ‘You’re round.’”
   
The joke is that “You’re round” (“You are round”) describes the circle’s shape, but “Your round” means that the circle must pay for drinks. The pun was posted on Twitter by Craig Colquhoun #BLM on April 5, 2011.
   
     
Twitter
Craig Colquhoun #BLM
@BobaFermi
A square and a circle walk into a bar. The square says to the circle, “your round”.
3:05 PM · Apr 5, 2011 from Glasgow City, Scotland·Twitter for iPhone
       
Twitter
Craig Whitney
@CWhitney7
A square and a circle walk into a bar.
“your round” said square
11:27 AM · Apr 22, 2015·Twitter for Android
   
Twitter
Andrew Luney
@AndrewLuney1
Replying to @conniegilmorex
@conniegilmorex @RobbieS1996 sqaure and a circle walk into a bar. Square turns amd says to the circle…your round!
6:17 PM · Apr 27, 2015·Twitter for Android
   
Twitter
Rajiv Sharma
@erajivsharma
A #square and a #circle walk into a bar. The square says to the circle, “Your round!” #jokes #smile #humor #enjoy #math
8:17 AM · Dec 7, 2015·Twitter Web App
 
Google Books
1001 Jokes in English
By Toni Yunanto
Black White
2018
Pg. ?:
504 A square and a circle walk into a bar. The square says to the circle, “Your round!”
   
Twitter
りょうま
@rymin13
A square and a circle walk into a bar, and the square says to the circle, “It’s your round”
こういうギャグが好き。自分の母語じゃないからなのか、日本語の親父ギャグよりもはるかにおもしろく感じる
12:34 AM · Nov 21, 2018·Twitter Web Client
 
Twitter
Lorraine Jo King
@lahlahbean
#badjokefriday
A square and a circle walk into a bar.
The square says to the circle, “you’re round.
1:52 AM · Jul 31, 2020·Twitter for iPhone