“What food are you able to can?”/“Cannibal (can able) food.”

A cannibal riddle is:
   
Q: What food are you able to can?
A: Cannibal (cannable) food.
 
The joke has been cited in print since at least 1976.
   
           
Google Books
Biggest Riddle Book in the World
By Joseph Rosenbloom
Illustrations by Joyce Behr
New York, NY: Sterling Publishing Company, Inc.
1976
Pg. 33:
What food are you able to can?
Cannibal (cannable) food.
 
9 April 2006, The Pantagraph (Bloomington, IL), “Riddle Me This,” Flying Horse sec., pg. ?:
Q: What food are you able to can?
A: Cannibal food.
 
Twitter
Bollywood Sargam‏
@bollywoodsargam
Food jokes - 5074 Joke: What food are you able to can?
Cannibal (can able) food. .... http://tinyurl.com/kqwhsm
7:07 PM - 11 Jul 2009
   
Google Books
Sensible Nonsense.. Frank’s Comic Pack:
Humour Pack Series
By Frank Paul
BookBaby
2014
Pg. ?:
What food are you able to can?Cannibal (can able) food.
   
Twitter
Verdie Caputi‏
@VerdieCaputi
What food are you able to can? Cannibal (can able) food.
2:10 AM - 2 May 2017
 
Twitter
Eliz Dejean‏
@ElizDejean
What food are you able to can? Cannibal (can able) food.
3:10 PM - 9 May 2017