“Why are mountains so funny? Because they’re hill areas”

“Why are mountains so funny? Because they’re hill areas” is a hilarious pun that has been printed on many images. The joke was posted by Dave Lee on Twitter on July 14, 2011.
 
   
Twitter
Dave Lee
‏@davelee
Why are mountains so funny? Because they’re hill areas.
11:41 AM - 14 Jul 2011 from Wandsworth, England
 
Twitter
Sam Holl
‏@samholl
Oh, christ… (I love it) RT @davelee: Why are mountains so funny? Because they’re hill areas.
11:48 AM - 14 Jul 2011
 
Twitter
Peter Moncrieff
‏@breakoutpete
Mountains aren’t funny. They’re hill areas.
2:05 PM - 27 Apr 2012
   
26 June 2013, The Advertiser (Adelaide, Australia), “Mouthing Off” by Marty Smith, pg. 22:
Riddle: Why are mountains so funny? Because they’re hill areas.
   
Google Books
Best Ever Classroom Jokes:
Because some of us never grow up

By Mike Haskins
New York, NY: Pavilion Books
2015  
Pg. ?:
Why are mountains so funny?
Because they’re hill areas.
 
Reddit—Jokes
Why are mountains so funny?
submitted February 16, 2015 by T0tai
Because they are hill areas.
I’ll show myself out
 
Reddit—Jokes
Mountain’s aren’t funny…
submitted October 9, 2016 by Pyronaut44
They’re hill areas.
 
Reddit—Dadjokes
Mountains aren’t just funny (self.dadjokes)
submitted October 11, 2016 by PKMKII
They’re hill areas.