“What kind of key opens a banana?”/“A monkey.”

A popular banana joke is:
 
Q: What kind of key opens a banana?
A: A monkey.
 
The joke has been cited in print since at least 2002.
 
   
Google Books
Over 1500 Fantastic Jokes
By Guy Campbell and Paul Moran
London: Dean
2002
Pg. 26:
What kind of key opens a banana?
A monkey!
 
Google Books
The Usborne Book of Really Awful Jokes:
About School and Other Stuff
By Laura Howell
Tulsa, OK: EDC Publishing
2003
Pg. 32:
Teacher: What kind of key opens a banana?
Pupil: That’s a trick question. You don’t need a key to open a banana.
Teacher: Wrong. The answer is a monkey.
   
Google Books
Blonde Walks into a Bar:
The 4,000 Most Hilarious, Gut-Busting Gags, One-Liners and Jokes
By Jonathan Swan
Berkeley, CA: Ulysses Press
2008
Pg. ?:
What kind of key opens a banana?
A monkey!
   
Google Groups: alt.appalachian
Nah, nah nah Boener
Guv Bob
1/25/13
(...)
LARRY: What kind of key opens a banana?
JOEVAN: A monkey!
   
reddit
What key opens a banana?
submitted October 8, 2014 by yoga_dogg
A monkey.
What key opens a carrot?
A donkey.
 
Twitter
Colibra
‏@_Colibra_
What kind of key opens a banana?
A monkey.
(Apparently, COLIBRA haven’t posted for 68 days. That’s all I’ve got.)
3:59 PM - 5 Oct 2015
 
Twitter
Speed Reaper ⚡
‏@TraackNation
What kind of key opens a banana? A monkey 🐒😂😂
9:52 PM - 5 Oct 2015
 
Twitter
102.5 BFBS Aldershot
‏@BFBSAldershot
Joke of the Day: What kind of key opens a Banana? A Monkey!
1:53 AM - 7 Oct 2015
 
Google Books
Animal Jokes
By Joe King
Marine Publishing
2016
Pg. ?:
Q: What kind of key opens a banana?
A: A monkey.
 
reddit
what key opens a banana? self.3amjokes
Submitted April 7, 2016 by [deleted]
monkey