“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” A rock version is:
 
“A rock walks into a bar. The bartender says, ‘We don’t serve your kind here.’ The rock says, ‘Why not? I’m a Gneiss guy!’”
     
The gneiss rock joke was posted on Twitter on March 2, 2010, and on Reddit—Jokes on January 13, 2018.
 
There have been several other “rock walks into a bar” versions. “A rock walks into a bar ‘can I have a double whiskey on the rocks’ and then they pour whiskey on him haha” was posted on April 27, 2012.
     
 
Twitter
Aimee Small‏
@aimeecarp
a rock walks into a bar. the bartender says, “we don’t serve your kind”. the rock says, “why not? i’m a Gneiss guy!” hahaha.
12:41 PM - 2 Mar 2010
           
Twitter
blindnascarfan Amy‏
@blindnascarfan
RT @NoTweetJeremy So a rock walks into a bar crying and sits down, the bartender says, ‘‘Why so sedimental?’’ LOL!love it! #FutureFBStatus!
12:06 AM - 6 Apr 2011
   
Twitter
Matt Novak‏
@paleofuture
Rock walks into a bar. Bartender says “looks like you’ve put on a few pounds.” Rock says “It’s my sedimentary lifestyle. Also, you’re mean.”
10:32 AM - 8 Feb 2012
   
Twitter
aidan wall‏
@aidowall
a rock walks into a bar “can I have a double whiskey on the rocks” and then they pour whiskey on him haha
11:07 AM - 27 Apr 2012
 
Twitter
Lindsay Harris-Friel‏
@thislindsay
Replying to @BillNye
@TheScienceGuy @IamStevenT: A Science Guy and a Rock Star walk into a bar. It was gneiss.
8:52 AM - 23 Sep 2013
   
Twitter
MOET KEEPS ME PISSY‏
@iAintAsianTho
why have you never heard a “a rock walks into a bar” joke?
because rocks don’t walk, they roll.
2:35 AM - 24 Apr 2014
 
Reddit—Jokes
A rock walks into a bar
submitted November 1, 2017 by DoctorLazertron
and orders a whiskey. The bartender says, Sorry we don’t serve rocks here.
“Neat.”
 
Reddit—Jokes
A rock walks into a bar
submitted January 13, 2018 by qaqwer
The bartender tells him “we don’t serve your kind here”
So the rock says: “Why not? I’m a gneiss guy!”