“Who digs the graves when the grave diggers go on strike?”/“The skeleton crew.”

A “skeleton crew” has the minimum number of people—and not actual skeletons—but there’s a Halloween riddle:
 
Q: Who digs the graves when the grave diggers go on strike?
A: The skeleton crew.
 
The joke was posted to the newsgroup alt.humor on October 15, 1998.
 
 
Wiktionary: skeleton crew
Noun
skeleton crew ‎(plural skeleton crews)
1. (idiomatic) The minimum number of personnel needed to operate and maintain an item at its most simple operating requirements, such as a ship or business, during an emergency or shut down, and at the same time, to keep vital functions operating.
 
Google Groups: alt.humor
Halloween Humor - 22
Craig Bennett
10/15/98
(...)
Who digs the graves when the grave diggers go on strike?
The skeleton crew!
 
Google Groups: alt.humor
Who digs the graves when the grave diggers go on strike?
Craig Bennett
10/17/01
Who digs the graves when the grave diggers go on strike?
The skeleton crew!
 
Google Groups: eunet.jokes
Who digs the graves when the grave diggers go on strike?
Peter The Great
10/31/02
Who digs the graves when the grave diggers go on strike?
The skeleton crew!
 
Google Groups: alt.humor.puns
Kids Puns of the Weak 10-26-04
Stan Kegel
10/26/04
(...)
Who digs the graves when the grave diggers go on strike?
The skeleton crew!.
   
Twitter
Tuffie Toys
‏@TuffieToys
Q: Who digs the graves when the grave diggers go on strike?
A: The skeleton crew!
8:56 PM - 31 Oct 2011
 
Google Books
Super Hot Jokes For Cool Kids!
By Various Authors
London: Buster Books
2014
Pg. ?:
Who digs graves when the gravediggers go on strike?
A skeleton crew.
 
Twitter
Babalou2
‏@robashworth
@spicysweet84
Q: Who digs graves when Gravedigger on vacation?
A: His skeleton crew! lol
4:59 PM - 16 Sep 2014
Cleveland, OH