“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” A Smurf version is:
 
“A Smurf walks into a bar. The bartender says, ‘Why so blue?’”
 
The joke was posted on Twitter on August 25, 2010, when it was credited to “Jeff Wignall, Stratford, Connecticut, USA.”
 
“What do you get when you cross a Smurf with a cow?”/“Blue cheese” is another Smurf joke.
   
 
Wikipedia: The Smurfs
The Smurfs (French: Les Schtroumpfs; Dutch: De Smurfen) is a Belgian comic franchise centered on a fictional colony of small blue anthropomorphous creatures who live in mushroom-shaped houses in the forest. The Smurfs was first created and introduced as a series of comic characters by the Belgian comics artist Peyo (pen name of Pierre Culliford) in 1958, where they were known as Les Schtroumpfs. There are more than one hundred Smurf characters, and their names are based on adjectives that emphasize their characteristics, such as “Jokey Smurf”, who likes to play practical jokes on his fellow smurfs. “Smurfette” was the first female Smurf to be introduced in the series. The Smurfs wear Phrygian caps, which came to represent freedom during the modern era.
 
Twitter
rawgardenuk‏
@Rawgarden
“A smurf walks into a bar. The bartender says, ‘Why so blue?’ ”Jeff Wignall, Stratford, Connecticut, USA
8:22 AM - 25 Aug 2010
 
Twitter
Emma Cooke‏
@emmac129
A smurf walks into a bar. The bartender says, ‘Why so blue?’
3:30 PM - 10 Nov 2010
 
Twitter
Ali‏
@ih8my3x
A smurf walks into a bar. The bartender says, ‘Why so blue?’
6:57 AM - 11 Jan 2011
 
Twitter
Rob Gotobed!‏
@robgotobed
A Smurf walks into a bar. The bartender says, ‘Why so blue?’
11:24 AM - 2 Mar 2011
     
Google Books
5,000 Sidesplitting Jokes and One-Liners
Compiled by Grant Tucker
New York, NY: Skyhorse Publishing
2013
Pg. ?:
A Smurf walks into a bar. The bartender says, ‘Why so blue?’
 
Twitter
Allan Dowdeswell‏
@confidant_ca
A green smurf walks into a bar. The bartender says “We don’t appreciate off-colour jokes here!” #fb
1:58 PM - 17 Sep 2017