“What kind of cup can’t hold water?”/“A cupcake.”

A popular food riddle is:
 
Q: What kind of cup can’t hold water?
A: A cupcake.
 
The joke has been cited in print since at least 2008.
 
     
Google Books 
Ha! Ha! Ha! and Much More:
The Ultimate Round-up of Jokes, Riddles, Facts & Puzzles
By Lyn Thomas
Toronto, ON: Maple Tree Press
2008
Pg. 210:
What kind of cup can’t hold water?
A cupcake.
 
slideshare
02 Riddlemethisbeerparty
jalopez
Published on Aug 27, 2008
(...)
5. Riddle Me This
What kind of cup can’t hold water?
- A cupcake. -
 
Twitter
Rose Jane
‏@vellaky
Q:What kind of cup can’t hold water? A:I’m stumped… http://formspring.me/chuffybarmed/q/571622995
7:37 AM - 20 May 2010
 
Twitter
Oly Grocery Outlet
‏@OlympiaGO
Bad Jke of the Day:  What kind of cup can’t hold water?  A cupcake!
10:44 AM - 23 Sep 2010
 
Facebook
Wendy’s DC/MD/NoVa
March 6, 2012 ·
What kind of cup can’t hold water ?