“A horse walks into a bar. The bartender says, ‘Hey!’ ...”

“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” A horse version is:
 
“A horse walks into a bar. The bartender says, ‘Hey!’ The horse says, ‘Yes, please!’”
 
“Hey” sounds like “hay.” “Horse walks into a bar. Bartender looks up and says: ‘Hey!’.  Horse sits down and says ‘Sure!’” was posted on the newsgroup rec.equestrian on July 29, 1998.
   
     
Google Groups: rec.equestrian
equestrian statues: meaning?
EquineDad
7/29/98
(...)
obhorsey:
Horse walks into a bar. Bartender looks up and
says: “Hey!”.  Horse sits down and says” “Sure!”.
       
Google Groups: alt.treasure.hunting
MXT XLT Explorer XS
Horseface
11/29/03
:`(
Horseface
A horse walks into a bar.  The bartender says, “Hey.”  The horse says,
“Sure.”
 
Google Groups: rec.gambling.lottery
Lotto Cheatah: How it works  
CDEX
12/13/03
(...)
Horse story (OT).  A horse walks into a bar.  Bartender waves and says,
“hey!”.  Horse says, “sure.”
 
Twitter
Lizzie Mary Cullen
@Lizzie_M_Cullen
A horse walks into a bar. The bar tender says “Hey.”
The horse says “Sure.”
2:16 AM · Apr 24, 2009·Twitter Web Client
     
Twitter
Joseph Cannizzaro
@dudeman718
#badjokes A horse walks into a bar. The bar tender says “Hey.”
The horse says “Sure.”
9:21 PM · Jul 17, 2009·Twitter Web Client
   
Twitter
Aaron Headly
@jonniebgoad
So a ‘horse’ walks into a bar & the bartender says:‘Hey!..(the horse says) “Yes, Please,I’m starved!”........#sorry!
12:18 PM · Oct 26, 2011·Twitter Web Client
   
Twitter
Grand National
@grandnational
A horse walks into a bar. The barman says “Hey”. The horse says “Yes, please” #Grandnationaljokes
6:01 AM · Apr 5, 2014·TweetDeck
 
Reddit—Jokes
Posted by u/habloun November 14, 2016
A horse walks into a bar…
The bartender says, “Hey.”
The horse says, “Sure.”
   
Reddit—Jokes
Posted by u/thenutmaster February 1, 2018
A horse walks into a bar,
Walks into a bar
The bartender says, “Hey!”
The horse replies, “Sure”.
 
Twitter
Ascot Racecourse
@Ascot
A horse walks into a bar.
“Hey,” says the barman.
“Yes please,” says the horse.
#NationalTellAJokeDay
Image
6:46 AM · Aug 16, 2018·Twitter Web Client
 
Reddit—Jokes
Posted by u/slenderman201 may 7, 2019
A horse walks into a bar
“Hey”, the Bartender says.
“Sure”, the horse replies.
 
LaffGaff
By laffgaff September 2, 2019
Grinning at really funny horse walks into bar jokeHorse Walks Into Bar Joke
A horse walks into a bar.
The bartender says, “Hey!”
The horse says, “Yes, please!”