“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” A dice version is:
 
“A pair of dice walk into a bar. The bartender asks, ‘What are you having, fellas?’ One die answers, ‘Doubles.’”
 
The infrequently told joke was cited on Twitter on June 20, 2009.
 
   
Twitter
Tom McMullen
‏@tommcmullenjr
A pair of dice walk into a bar. The bartender asks, “What are you having, fellas?”  One die answers, “Doubles”  #WalksIntoABar
2:40 PM - 20 Jun 2009
 
wb4all
July 13, 2009
Cool Dumb Jokes: “Walks Into A Bar” 😊
(...)
A pair of dice walk into a bar. The bartender asks, “What are you having, fellas?” One die answers, “Doubles”
 
Deb Runs
My Favorite Walked Into A Bar Jokes
October 22, 2015 Written by Deb Runs
(...)
A pair of dice walk into a bar.  The bartender asks, “What are you having, fellas?”  One die answers, “Doubles.”