“What do you get when you cross a kangaroo with a calendar?”/“A leap year.”

A leap year riddle is:
     
Q: What do you get when you cross a kangaroo with a calendar?
A: A leap year.
   
The riddle has been cited in print since at least 1994. “What is a kangaroo’s favorite year?”/“A leap year” is a similar riddle.
         
     
Newspapers.com
16 February 1994, Victoria (TX) Advocate, “Kids Life,” pg. 8B, col. 1:
What do you get when you cross a kangaroo with a calendar?
Leap year.
 
Newspapers.com
24 January 1997, Ravalli Republic (Hamilton, MT), “A Little Bit of Humor,” Connection sec., pg. 8, col. 1:
Clay: What do you get if you cross a kangaroo with a calendar?
Robbie: Leap year.
 
Newspapers.com
30 September 2001, The Sun (Baltimore, MD), “Riddles ‘n’ Giggles,” sec. 2, pg. 2, col. 5:
WHAT DO YOU GET IF YOU CROSS A KANGAROO AND A CALENDAR?
LEAP YEAR
     
29 February 2008, Townsville (Queensland) Bulletin, “Make the most of the extra day” by Mary Vernon, pg. 18:
What do you get when you cross a kangaroo with a calendar?
A leap year.
 
Twitter
Rob Wareham
@Selmech
What do you get if you cross a kangaroo with a calendar?
3:41 PM · Jan 7, 2010·Twitter Web Client
 
Twitter 
Seyi Fowode
@SFowode
What do you get when you cross a kangaroo with a calendar? A leap year! http://fb.me/urb8QaVy
1:30 PM · Apr 8, 2010·Facebook
   
Twitter
Gof
@qafro
What do you get when you cross a kangaroo with a calendar?
A leap year!#joke
9:42 AM · Jul 21, 2010·Twitter Web Client
   
Twitter
The Creative J
@TheCreativeJ
What do you get when you cross a kangaroo with a calendar? http://r8t.us/mMLxnU
11:02 AM · Jun 21, 2011·RatePoint
 
Twitter
Joke of the Day Bot
@JokeOfTheDayBot
What do you get when you cross a kangaroo with a calendar?
A leap year.
12:12 PM · Oct 17, 2019·Honors 350 bot