“A guy walks into a bar…” is a typical form of what has been called the “bar joke.” An astronomy version is:
 
“A black hole walks into a bar. It tells the bartender, ‘Nothing light.’”
 
The joke was posted on Reddit—Jokes on June 8, 2017.
 
There have been several other punchlines. “A black hole walks into a bar.‘“Hey, you can’t come in here!’ says bartender. ‘Why not?’ asks the black hole. ‘Because u suck!’” was posted on Twitter on January 17, 2010.
 
“A black hole walks into a bar and orders a drink. The bartender asks if he’d like food with that. The black hole said ‘no thanks, I’m a light eater’” was posted on Reddit—Jokes on May 10, 2018.
     
     
Wikipedia: Black hole
A black hole is a region of spacetime exhibiting such strong gravitational effects that nothing—not even particles and electromagnetic radiation such as light—can escape from inside it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, no locally detectable features appear to be observed. In many ways a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.
   
Twitter
★ amanda bauer ★‏
@astropixie
a black hole walks into a bar and says “where’d everybody go?”
9:18 AM - 12 May 2009
 
Twitter   
Holly‏
@absolutspacegrl
A black hole walks into a bar. “Hey, you can’t come in here!” says bartender. “Why not?” asks the black hole. “Because u suck!” @astroengine
1:55 PM - 17 Jan 2010
 
Twitter
Steph‏
@sstephh
“a black hole walks into a bar…...life on that planet comes to an end, and the planet is annihilated.” i think i just died
4:16 PM - 20 Nov 2010
 
Twitter
JD the Kid‏
@MmmBaecon
A black hole walks into a bar. #EveryoneDies
10:49 PM - 27 Sep 2011
 
Twitter
Timothy Stapleton‏
@TheGoodTim
A black hole walks into a bar and everyone disappears. #usguys
3:56 PM - 9 Dec 2011
 
Twitter
People’s Atheist‏
@PplsAtheist
@weakSquare a black hole walks into a bar, bartender says “why the long particle jet?”
11:15 AM - 10 Dec 2014
 
Twitter
Longsands Science‏
@LongsandsSCI
A black hole walks into a bar and says to the guy next to him “Do you realise the gravity of this situation?”!
2:49 PM - 11 Nov 2015
 
Reddit—Jokes
A black hole walks in to a bar
submitted June 8, 2017 by johnnylovelace
It tells the bartender, “nothing light.”
 
Reddit—Jokes
A black hole walks into a bar and orders a drink…
submitted May 10, 2018 by samtheman66
The bartender asks if he’d like food with that.
 
The black hole said “no thanks, I’m a light eater.”