“What did one plate say to the other?”/“Lunch is on me.”

A popular children’s riddle is:
 
Q: What did one plate say to another?
A: Lunch is on me!
 
The riddle has been cited in print since at least 1998. “Dinner is one me!” is a variant.
 
 
Google Groups: comp.internet.net-happenings
K12> Friday’s KID KLICKS - The White House for Kids
Gleason Sackman
10/23/98
Today’s
Question:  What did one plate say to the other plate?
(...)
Today’s
Answer:  Lunch is on me!
 
28 May 1999, Aberdeen (SD) American News, Farm Forum, pg. 51F, col. 2:
“What did one plate say to the other plate?”
“Lunch is on me!”
 
Google Books
Funny Boy Takes on the Chitchatting Cheese from Chattanooga
By Dan Gutman
New York, NY: Hyperion Book CH
2000
Pg. 44:
“What did one plate say to the other?” I asked.
“What?”
“Lunch is on me.”
   
Google Books
November 2001, Boys’ Life, “Think & Grin,” pg. 73, col. 2:
Jake: What did one plate say to the other plate?
Drake: What?
Jake: “Lunch is on me!” — Julia Lue Phang, Ooltewah, Tenn.
 
Google Groups: alt.humor.puns
Puns of the Weak 11/16/01
Stan Kegel
11/17/01
(...)
What did one plate say to the other?
‘Dinner’s on me!’  (Syman Hirsch) 
 
Google Books
Jokelopedia:
The Biggest, Best, Silliest, Dumbest, Joke Book Ever
Edited by Ilana Weitzman
New York, NY: Workman Publishing Company, Inc.
2006
Pg. 25:
What did one plate say to the other?
“Dinner’s on me. “
 
Twitter
TapRoot
‏@TapRootAK
Q:What did one plate say to the other plate? A:(‘Lunch is on me!’)....
.....sunday food funny for you 😉
7:25 PM - 1 Mar 2009
 
Twitter
Sarah Boone
‏@sarahxboone
@TranquilMammoth what did one plate say to the other?” Dinners on me”
5:47 PM - 5 May 2009