“A guy walks into a bar...” is a typical form of what has been called the “bar joke.” A dwarf version is:

“A dwarf walks into a bar. The bar for this joke is set pretty low.”

“A dwarf, a gnome and a hafling all walk into a bar...’OW!’ ...That bar would have to be set pretty low. Much like your standards. HA!” was posted on Twitter on October 24, 2009. “A dwarf walks into a bar and hits his head. This joke set the bar pretty low” was posted on Twitter on May 24, 2013. “A dwarf walked into a bar. The bar for this joke is set pretty low” was posted on Reddit—Jokes on December 17, 2017.

“A midget walks into a bar...” is a related joke.


Twitter
Elle‏
@2HeartedGinger
A dwarf, a gnome and a hafling all walk into a bar..."OW!" ...That bar would have to be set pretty low. Much like your standards. HA!
10:12 AM - 24 Oct 2009

Twitter
Adoree‏
@WoWAdoree
A gnome and a dwarf walk into a bar. They really set the bar low.
12:29 AM - 3 Mar 2013

Twitter
dross dossier‏
@bi1yeu
A dwarf walks into a bar and hits his head.
This joke set the bar
pretty low.
2:18 PM - 24 May 2013

Twitter
GreyMaster‏
@_GreyMaster
A Dwarf and a Hobbit walk into a bar...we shouldn’t have set the bar so low.
6:49 PM - 19 Jun 2016

Twitter
TrueReckons‏
@Sherida7William
Replying to @11Kstew70
If it’s for a short story then the joke might be: “A dwarf walks into a bar… The bar was set low”
3:19 AM - 26 Aug 2016

Reddit—Jokes
A dwarf walked into a bar.
submitted December 17, 2017 by toforama
The bar for this joke is set pretty low.

Reddit—Dad Jokes
A dwarf walked into a bar. (self.dadjokes)
submitted December 17, 2017 by toforama
The bar for this joke is set pretty low.
(Posted this on r/jokes but just strikes me as belonging here too....)