“What do you get if you cross a sheepdog with a jelly?”/“The collie-wobbles.”

Jelly wobbles, and a riddle is:
   
Q: What do you get if you cross a sheepdog with a jelly?
A: The collie-wobbles.

     
“Collywobbles” means a stomachache or anxiety, fear. The joke has been cited in print since at least 1978.
   
“What wobbles and flies?”/“A jellycopter” is another jelly riddle.
   
       
Wiktionary: Collywobbles
Noun
collywobbles

1. (plural only, informal) Stomachache. [From 1823]
2. (plural only, informal) Anxiety, fear
         
Google Books
The Crack-A-Joke Book
Harmondsworth, UK: Penguin Books
1978    
Pg. 48:
What do you get when you cross a jelly with a sheep dog?
Collie-wobbles.
 
Google Books
Linguistics for Students of Literature
By Elizabeth Closs Traugott
New York, NY: Harcourt Brace Jovanovich
1980
Pg. 264:
What do you get when you cross a jelly with a sheepdog? (Collie-wobbles.) (Collie-wobbles = American “growling stomach.”)
 
Google Groups: alt.humor.puns
!!!!!!!!!!!!!!!!!!!!!!!!! BBC RADIO 7 FORCE HAIL !!!!!!!!!!!!!!!!!!!!!!!!!!!! What, what, what, what, what, what, what, what?!
Stan Kegel
12/21/02
Tom Carr wrote:
(...)
> > What do you get if you cross a jelly and a sheepdog?
> > Right answer: Collie Wobbles!
   
Google Books
Penguin Pocket Jokes
By David Pickering
London, UK: Penguin Books
2006
Pg. ?:
What do you get if you cross a sheepdog with a plate of jelly?
Collie-wobbles.
 
6 August 2006, Sunday Mail (Glasgow, Scotland), “Funnies,” pg. 3:
What do you get when you cross a jelly with a sheepdog?
Collie-wobbles.
 
Twitter
Bev and Roger Nevard
@rbnevard
Joke - Dog jokes: What do you get if you cross a sheepdog with a   jelly ? ... http://76k.com/j/c0dhlb
12:25 AM - 15 Dec 2009
 
Twitter
PaulitaBrBarbar
@PaulitaBrBarbar
What do you get if you cross a sheepdog with a jelly ? The collie wobbles !
1:47 PM - 13 Jan 2010
 
Twitter
Lucky Score
@LuckyScoreNet
What do you get if you cross a sheepdog with a
jelly ?
The collie wobbles !
#Joke from #DogJokes in #Jokes, #Humor and #Satire
1:03 AM - 30 Jan 2018