“Poisoned coffee, n: Grounds for divorce”

A pun has it that “poisoned coffee is grounds for divorce.” The joke has been cited in print since at least 1968.
   
“Poisoned coffee, n.: Grounds for divorce” has been cited since at least 1999.
 
   
11 December 1968, Tucson (AZ) Daily Citizen, “Tucson School System Is Shelled WIth ‘New Humor’” by Patt Morrison, pg. 40, col. 3:
Two days ago, the Supreme Court ruled that poisoned coffee is grounds for divorce.
 
Google Groups: rec.humor
Some short jokes
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1/13/90
(...)
What do you call poisoned coffee?  - - - Grounds for divorce.
 
Google Groups: pl.test
g
Kamil Jonca
8/3/99
(...)
poisoned coffee, n.:
Grounds for divorce.
 
Google Groups: Joke of The Day
JOKE OF THE DAY 13 Dec 2005
Chirag Gupta
12/13/05
(...)
* Is poisoned coffee grounds for divorce?
   
Twitter
BSDfortune
‏@bsdfortune
poisoned coffee, n:
Grounds for divorce.
12:08 PM - 11 Jul 2009
 
Twitter
web-geek.com
‏@webgeekcom
poisoned coffee, n: Grounds for divorce.
1:55 AM - 1 Sep 2009
 
Twitter
fortune-bot
‏@robot_fortune
poisoned coffee, n.:
Grounds for divorce.
2:00 AM - 12 Feb 2016