“What’s the hardest thing to sell to a ghost?”/“Life insurance.”

A ghost riddle is:
 
Q: What’s the hardest thing to sell to a ghost?
A: Life insurance.
 
The life insurance joke has been cited in print since at least 1992.
 
       
Google Books
102 Haunted House Jokes
By Ski Michaels
Mahwah, NJ: Watermill Press
1992
Pg. 52:
What’s the hardest thing to sell to a ghost?
Life insurance.
 
29 October 2003, The Monitor (McAllen, TX), “Weekly Writing Corner: Halloween Humor,” pg 8B, col. 8:
What’s the hardest thing to sell to a ghost?
Life insurance.
Ariana Maldonado, 4th grade, De la Vina Elementary
 
Twitter
BeynonCompany
@BeynonCompany
Q: What is the hardest thing to sell to a ghost?
A: Life insurance!
10:00 PM - 24 Jul 2015
   
Twitter
Celia Insurance
@CeliaInsurance
“What’s the hardest thing to sell to a ghost?”
          -Life Insurance http://ow.ly/D7aW302WOOh
11:02 AM - 23 Aug 2016
   
Twitter
HEERA PATEL
@mheera65
What is the hardest thing to sell to a Ghost? Ans:LIFE insurance!! @SRKUniverse @RedChilliesEnt #GoodBadJokes
6:54 AM - 22 Oct 2016
 
Twitter
lorraine Jo King
‏@LahLahBean
#jokes
What’s the hardest thing to sell to a ghost?
Life insurance!
3:23 PM - 30 Jul 2018