“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” One food joke variation is:
 
“A ham sandwich walks into a bar and begins to order. The bartender stops him and says, ‘We don’t serve ham sandwiches here.’ The sandwich says, ‘That’s OK. I just wanted a beer.’”
 
The joke has been cited in print since at least 2004. Other foods have been used in the joke besides a ham sandwich, such as a mushroom and a chicken.
 
A shortened (and older) form of the joke is when the bartender replies, “We don’t serve food.”
     
   
LetsSingIt Forum
VinylAGoGo
04-10-2004 02:51
(...)
a ham sandwich walks into a bar and begins to order. the bartender interrupts him with, “we don’t serve ham sandwiches here.” the sandwich says, “that’s OK, i just wanted a beer.” 

Google Groups: novell.community.chat
I’m just so happy I could just
Sewermonger Smurf or Till Sandybanks of Frogmorton
5/19/04
A ham sandwich walks into a bar
and begins to order. The bartender stops him
and says “We don’t serve ham sandwiches here”.
The sandwich says “That’s OK, I just wanted a beer”.
 
Forums of Loathing
Really Bad Joke Thread
cheese152
Tue, Jul 31st, 2007, 03:42 PM
So a mushroom walks into a bar. The bartender says “We don’t serve mushrooms here.”
The mushroom says “What I’m a fungi?”
 
So a mushroom walks into a bar. The bartender says “We don’t serve mushrooms here.”
The mushroom says “That’s okay I only wanted a beer”
 
Twitter
Hannah
‏@asdfghannah
A dog walks into a bar and orders a beer. The bartender says, “Sorry, we don’t serve dogs here”. He said, ‘That’s fine, I wanted a beer…’
12:43 PM - 6 May 2011
 
Twitter
David McLaughlin
‏@davidmac1992
@colewbennett Chicken walks into a bar. Bartender says, “We don’t serve poultry!”
Chicken says, “That’s ok, I just want a beer”
12:28 AM - 6 Oct 2014
 
Twitter
Stephen Fox
‏@s_fox10
@Rim_Jab ham sandwich walks into a bar. Bartender says “hey we don’t serve ham sandwiches”. Ham sandwich says “thats ok i just want a beer”
12:13 AM - 11 Apr 2015