“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” A pig version has one pig enter a bar, take a drink and use the bathroom. Another pig enters the bar, takes a drink and uses the bathroom. A third pig enters and takes a drink. The bartender tells him where the bathroom is. “No thanks,” says the pig, “I’m the one who goes ‘wee wee wee all the way home.’”
 
The pig bar joke has been cited in print since at least 1995.
 
     
Wikipedia: This Little Piggy
“This Little Piggy” or “This little pig” is an English language nursery rhyme and fingerplay. It has a Roud Folk Song Index number of 19297.
 
Lyrics 
The most common modern version is:
 
Words
This little piggy went to market,
This little piggy stayed home,
This little piggy had roast beef,
This little piggy had none,
And this little piggy went wee wee wee all the way home.
 
Google Groups: rec.humor
need pig jokes
Rain
4/23/95
> ‘nuf said….anyone???
Forgive me if this one was posted here before.
 
A pig goes into a bar.  He orders a drink and after two sips he asks the bartender where the bathroom is.
 
A few minutes later, a second pig enters, orders a drink and after a few sips asks the bartender where the bathroom is.
 
Soon after, a third little pig comes in, sits at the bar and orders a drink.  He sits there sipping it and the bartender comes up to him and asks, “Aren’t you going to ask me where the bathroom is?”
 
The pig replies, no, I am the pig that went “wee wee wee” all the way home.
 
Google Groups: k12.chat.junior
IF YOU HAVE ANY JOKES TYPE THEM IN THIS FILE
Ashley Chance
9/22/95
(...)
One day this little pig walks into a bar and says to the bartender that he wants ten drinks.  THe bartender told him he couldn’t drink ten drinks, but the pig did anyway.  Then he asked where the bathroom was, and the bartender told him down the hall and to the right.  The next day, another little pig walks into the bar and orders 100 drinks.  The bartender told him he couldn’t drink 100 drinks, but he did anyway.  When he was done, he asked where the bathroom was, and the bartender told down the hall and to the right.  The next day *another* little pig walks into the bar and orders 1000 drinks.  The bartender told him he couldn’t drink 1000 drinks but he did anyway.  When he was through, the bartender asked “Aren’t you doing to ask where the bathroom is?” and the little pig says “No, I’m the little pig that goes wee wee wee all the way home.”
 
Google Groups: alt.tasteless.jokes
Pigs in a bar
.(JavaScript must be enabled to view this email address)
7/31/96
Six pigs go into a bar.  All of them stay for about 3 hours, drinking as many drinks as they could. (Which was alot).  Five of the pigs use the bathroom quite often, but one of the pigs NEVER used the bathroom once
during the time he was there.  The barender noticed this and went over and talked with the pig. “Say, just out of curiosity, why haven’t you used the john?”  The pig answers,“Because I’m the little pig that goes wee wee-wee all the way home!”
 
Google Groups: alt.humor.puns
You’re today’s victim
Stan Kegel
7/18/98
(...)
One day a little pig walked into a bar. He drank a couple, then got up to leave. he asked the bartender, “Which way to the bathroom?” She answered, “Go down the hall, first door on your left.” The pig went to the bathroom and left. The next day another little pig came into the bar. he also had a few drinks, and asked the bartender where the bathroom was. Again, she told him, “Go down the hall, first door on your left.” Again, he went to the bathroom and left. This went on for another week. One day a pig walked in. he had a few drinks, but he got up and started to walk out. The bartender stopped him and asked, “Aren’t you going to ask where the bathroom is?” The little pig replied “No, i’m going wee wee wee all the way home.”
 
Google Groups: rec.music.artists.amy-grant
pig joke
FriendOfImp
3/19/01
This is totally non-Amy related, but it is cute… so read on.
 
A pig walks into a bar, orders 15 beers and proceeds to consume them all.  As he is about to leave, the bartender asks him how he could drink so much without having to go to the bathroom.  The pig replies: I’m the one who goes wee, wee, wee all the way home.
 
Google Books
Man Walks into a Bar:
Over 6,000 of the Most Hilarious Jokes, Funniest Gut-Busting One-Liners
By Stephen Arnott and Mike Haskins
Berkeley, CA: Ulysses Press
2007
Pg. 115:
A little pig walks into a bar, orders a drink and asks direction to the restroom. The bartender tells him where it is and the pig hurries off to relieve himself. A second little pig then comes in, orders a drink and asks for the restroom. Again the bartender tells the pig where to go and the pig hurries away. A third little pig then appears and orders a drink. “I suppose you’ll want to know where the men’s room is,” says the bartender. “No,” replies the pig. “I’m the one that goes wee-wee-wee all the way home.”
 
Google Groups: Americas-Graffitti
A pig walked into a bar
Sandra Carson
9/30/13
A pig walked into a bar and asked, “Do you serve root beer?”
The bartender said he did. “I’d like one, please,” the pig said.
After the pig had finished, he asked to use the rest room.
After the pig left, another pig came in and asked for two root beers.
This pig then asked for the rest room just like the first one had.
Two more pigs came in. One ordered three root beers and the other four.
They too used the rest room.
When a fifth pig came in, the bartender said, “Let me guess, you want five root beers.”
The pig was shocked. “Why, yes. Yes, I would.”
When he was done he started to walk out.
The bartender was confused. “Don’t you want to use the rest room like the other four pigs did?”
“No, I’m the fifth little piggy. I go wee-wee-wee all the way home.”