“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” A Beach Boys version is:
 
The Beach Boys walk into a bar
“Round?”
“Round?”
“Get a round”
“I get a round?”
“Get a round….”
 
The pun is on the Beach Boys’ song “I Get Around” (1964). The joke has been cited in print since at least March 2009.
     
       
Wikipedia: I Get Around
“I Get Around” is a song written by Brian Wilson and Mike Love for American rock band the Beach Boys. It was released as a single in May 1964 with “Don’t Worry Baby” as its B-side and became the group’s first number-one charting song in the United States. In the United Kingdom, it charted at number seven and was the band’s first top ten single there. It was included as the opening track on their studio album All Summer Long in July 1964.
     
Bodybuilding.com
The beach boys walk into a bar
tubz 
03-08-2009, 10:24 AM #1
“Round?”
“Round?”
“Get a round”
“I get a round?”
“Get a round….”
 
Twitter
Dave Lee‏
@davelee
Morning everyone! May I present: The Beach Boys walk into a bar
“Round?”
“Round?”
“Get a round”
“I get a round?”
“Get a round….”
4:54 AM - 9 Mar 2009
 
Twitter
Alex Tew‏
@tewy
The Beach Boys walk into a bar: “Round?” “Round?” “Get a round” “I get a round?” “Get a round….” #mondayjoke
8:20 AM - 9 Mar 2009
     
Live105 (San Francisco, CA)
10 Funniest Music Jokes
October 11, 2011 9:19 AM
(...)
3 )
Two Beach Boys walk into a bar. “Round?” “Round.” “Get a round?” “I’ll get a round!”
 
YouTube
The Beach Boys - I Get Around
John OneCOne
Published on Aug 23, 2013
     
Independent (London, UK)
International Day of Happiness: Best jokes ever (possibly)
There’s even one in the caption above
Stuart Henderson Thursday 20 March 2014 12:30 GMT
(...)
The Beach Boys walk into a bar. One says to the other “Round? Round? Get a round? I get a round?”
       
Facebook
Dad Joke of the Day
November 1, 2015 ·
The Beach Boys walk into a bar
“Round?”
“Round?”
“Get a round”
“I get a round?”
“Get a round….”
 
25 February 2016, Daily Star (London, UK), pg. 21:
ALAN WALL, Stoke
THE Beach Boys walk into a bar. One says to another: “Round? Round? Get a round? I get a round?”
     
Google Books
The Herald Diary:
Somebunny Loves You
By Ken Smith
Edinburgh, Scotland: Black & White Publishing Ltd
2017
Pg. ?:
Says a Hyndland reader: “That reminds me of the old joke, ‘The Beach Boys walk into a bar. ‘Round?’ ‘Round’. ‘Get a round’. ‘I get a round’.”
 
Twitter
Dad Jokes‏
@Dadsaysjokes
Two Beach Boys walk into a bar. “Round?” “Round.” “Get a round?” “I’ll get a round!”
4:07 PM - 23 Nov 2017