“What did the gingerbread man put on his bed?”/“A cookie sheet.”

A popular winter joke for children is:
 
Q: What did the Gingerbread Man put on his bed?
A: A cookie sheet.
 
The joke has been cited in print since at least 1998.
 
 
Google Books
Best Riddle Book Ever
By Charles Keller
New York, NY: Sterling Publishing Company, Inc.
1998
Pg. 23:
What did the gingerbread man have on his bed?
Cookie sheets.
 
Google Groups: uwo.comp.helpdesk
Humor: [GCFL] Santa Funnies
Heisey, Tom
12/22/00
(...)
What did the Gingerbread Man put on his bed?
A cookie sheet.
 
19 December 2008, Shelbrook (Saskatchewan) Chronicle, “Christmas Jokes and Riddles,” Christmas Edition, pg. 22, col. 5:
Q. What did the Gingerbread Man put on his bed? A. A cookie sheet!
 
Twitter
Payton Frisinger
‏@PaytonFrie13
“What does the gingerbread man put on his bed?”
“Cookie sheets”
#JokesFromMyMom
1:25 PM - 6 Dec 2015
 
Twitter
Dion Fawcett
‏@dionfawcett
What did the Ginergerbread man put on his bed? .................... A baking sheet! #HA #ChristmasJokes
6:44 PM - 6 Dec 2015