“What did one frog say to the other?”/“Time’s sure fun when you’re having flies.”

“Time flies when you’re having fun” is a popular saying. A joke transposing words is:
 
Q: What did one frog say to the other?
A: Time’s sure fun when you’re having flies.
     
The joke has been cited in print since at least 1977 and has been printed on many images.  “Time’s fun when you’re having flies, Kermit said” is another version of the joke. The Muppet character of Kermit the Frog is often associated with the joke, but did not originate it.
     
   
9 July 1977, The Courier-Journal (Louisville, KY), “Hoosier Journal” by Patricia Fischer, pg. 4, col. 2:
On a recent show about spiders
“Times sure is fun when you’re having flies.”
 
6 March 1978, The Arizona Republic (Phoenix, AZ), Paul Dean column, pg. B-1, col. 2:
ODDSERVATION: Blame Harriet for repeating this conversation between two frogs. “Time’s sure fun when you’re having flies.”
   
12 July 1979, Centre Daily Times (State College, PA), pg. 1, col. 6:
SWITCH: Bob Orben claims one frog said to another, “Time’s sure fun when you’re having flies!”
 
Google Books
December 1979, Boys’ Life “Think & Grin,” pg. 81, col. 2:
One frog to another: “Time’s sure fun when you’re having flies.” — Darryl R. Booth, Clovis, Calif.
   
4 July 1982, New York (NY) Times, “Frog’s Leap: A Prince of a Wine” by Terry Robards, pg. 34, col. 3:
She wasn’t aware that Frog’s Leap has a motto. Without much prodding, Mr. Williams will divulge it: “Time’s fun when you’re having flies.”
     
31 August 1983, Newsday (Long Island, NY), “Smiles,” Kidsday, pg, B38:
Ellen: What did one frog say to the other frog.
Angelin: Time’s fun when you’re having flies.
—Christa Castiglia, Lindenhurst
 
Google Books
January 1985, Boys’ Life, “Think & Grin,” pg. 64, col. 2:
Kermit: What did one frog say to another?
Miss Piggy: I don’t know. What?
Kermit: Time’s sure fun when you’re having flies.— Andrew Moschell, Kenosha, Wis.
     
Google Books
Get Thee to a Punnery:
An Anthology of Intentional Assaults Upon the English Language
By Richard Lederer
Layton, UT: Gibbs Smith
2006
Pg. 24:
One frog to another: Time’s fun when you’re having flies.
 
Twitter
Tracey‏
@Phyrdancer
“Time’s fun when you’re having flies.”
—Kermit the Frog
11:30 AM - 12 Jul 2007
 
Google Books
I Totally Funniest:
A Middle School Story
By James Patterson and Chris Grabenstein
New York, NY: Little, Brown
2015
Pg. ?:
Uh, Kermit the Frog: ‘Time’s fun when you’re having flies.’”
     
Twitter
Lucky Score‏
@LuckyScoreNet
What did one frog say.to the other?
Time’s
sure fun when you’re having flies!
#Joke from #FrogJokes in #Jokes,  #Humor and #Satire
11:05 AM - 28 Jun 2017