“When do cannibals leave the table?”/“When everyone’s eaten.”

A popular cannibalism joke is:
 
Q: When do cannibals leave the table?
A: When everyone’s eaten.
 
The joke has been cited in print since at least 1996. Another popular cannibalism joke is: “Why don’t cannibals eat clowns?”/“Because they taste funny!”
 
 
Google Groups: soc.culture.hawaii
The Cannibalism Post…
John Long
5/9/96
(...)
When do cannibals leave the table? When everyone’s eaten.
 
Google Groups: rec.humor
CANNIBAL
Nancy Carson
10/23/96
-When do cannibals leave the table?  When everyone’s eaten.
 
Google Groups: rec.food.cooking
Cannibal Cousine 😊
PENMART10
9/20/97
(...)
When do cannibals leave the table?
When everyone’s eaten.
 
Google Books
Over 1500 Fantastic Jokes
By Guy Campbell and Paul Moran
London: Dean
2002
Pg. 229:
When do cannibals leave the table?
When everyone’s eaten!
 
Google Books
The Mammoth Book of One-Liners
By Geoff Tibballs
London: Constable & Robinson Ltd.
2012
Pg. ?:
When do cannibals leave the table?
When everyone’s eaten.
 
Twitter
Clean Jokes
‏@CleanJokes247
#CleanJokes Q: When do cannibals leave the table? A: When everyone’s eaten. http://ow.ly/39Mo6Z
8:31 AM - 6 Jan 2016