“Why is history like a fruit cake?”/“Because it’s full of dates.”

A popular fruit cake joke is:
 
Q: Why is history like a fruit cake?
A: Because it’s full of dates.
 
The joke has been cited in print since at least 2000.
 
     
Google Books
1001 Really Stupid Jokes
By Mike Phillips
London: Constable & Robinson Ltd
2000
Pg. ?:
Why is history like a fruit cake?
Because it’s full of dates.
 
Google Books
Dude, Got Another Joke?
By Bob Phillips
Eugene, OR: Harvest House Publishers
2002
Pg. 45:
Edgar: Why is history like a fruitcake?
Egor: I have no clue.
Edgar: Because it’s full of dates.
 
CoffeeCakes.com (December 16, 2003)
Fruit cake
We’ve all heard them – the infamous fruitcake jokes! “Why is history like a fruit cake? Because it is full of dates!”
   
Lawrence (KS) Journal-World
Fabulously fruity?
Holiday cake struggles with uphill battle for popularity
By Terry Rombeck
December 7, 2005
(...)
Why is history like a fruitcake? Because it’s full of dates.
 
Google Books
Penguin Pocket Jokes
By David Pickering
New York, NY: Penguin Books
2006
Pg. ?:
Why is history like a fruit cake?
Because it is full of dates.
 
Fresh for Kids (May 24, 2007)
Q: Why is History like a fruit cake?
A: Because it’s full of dates!
From Samantha Turner from Hassall Grove
NSW
Age 11
 
Twitter
Nexus Art Café
‏@NexusArtCafe
What is the fruitiest lesson?History, because it’s full of dates!
1:22 PM - 20 Apr 2009
 
Twitter
Big Girl Branding
‏@BigGirlBranding
Joke of the day- What is the fruitiest lesson?  History, because it’s full of dates!
10:03 AM - 26 May 2009
 
Twitter
JOE TODD
‏@MYQUALITYTIME
Why is history like a fruit cake? Because it is full of Dates.
Just thinking about food
8:37 AM - 4 Jun 2009
   
Google Books
Learning about Language:
Activities for the Primary Classroom
By John Foster
New York, NY: Routledge
2012
Pg. 145:
Q. Why do history teachers like fruit cake?
A. Because it is full of dates.
 
Facebook
The ‘Khoji’ Cook
September 4, 2013
Why is History like a fruit cake? Because it’s full of dates!