“What’s the difference between 9/11 and a cow?”/“You can’t milk a cow for X years.”

The September 11, 2001 attacks on the World Trade Center and the Pentagon were a national tragedy, but some have been accused of profiting (or “milking”) the tragedy too much for personal gain. A joke was cited in print in January 2008 about former New York City mayor Rudy Giuliani:
 
Q: What’s the difference between 9/11 and a cow?
A: Rudy Giuliani doesn’t know how to milk a cow.
 
“What’s the difference between 9/11 and a cow? Americans don’t know how to milk a cow!” was cited on Twitter on April 29, 2009.
 
The punchline soon changed a bit. “What’s the difference between 9/11 and a cow? You can’t milk a cow continuously for 8 years” was cited on Twitter on November 19, 2009. “What’s the difference between 9/11 and a cow? You can’t milk a cow for 8 years” was tweeted on November 20, 2009. This joke—sometimes offensive, depending on the context and the audience—has remained popular, with the number of years increasing every year from 2001.
 
“What’s the difference between a cow and the Holocaust?” is a variation of the “milk a cow” phrase for another tragic event.
 
   
Wikipedia: September 11 attacks
The September 11 attacks (also referred to as 9/11) were a series of four coordinated terrorist attacks by the Islamic terrorist group al-Qaeda on the United States on the morning of September 11, 2001. The attacks killed 2,996 people and injured 6,000 others and caused at least $10 billion in property and infrastructure damage and $3 trillion in total costs.
 
Four passenger airliners operated by two major U.S. passenger air carriers (United Airlines and American Airlines)—all of which departed from airports on the northeastern United States bound for California—were hijacked by 19 al-Qaeda terrorists. Two of the planes, American Airlines Flight 11 and United Airlines Flight 175, were crashed into the North and South towers, respectively, of the World Trade Center complex in New York City. Within an hour and 42 minutes, both 110-story towers collapsed, with debris and the resulting fires causing partial or complete collapse of all other buildings in the World Trade Center complex, including the 47-story 7 World Trade Center tower, as well as significant damage to ten other large surrounding structures. A third plane, American Airlines Flight 77, was crashed into the Pentagon (the headquarters of the United States Department of Defense) in Arlington County, Virginia, leading to a partial collapse of the building’s western side.
   
To Which I Replied…
What’s the difference between 9/11 and a cow?
Rudy Giuliani doesn’t know how to milk a cow.
Posted by Fletch at 1/09/2008
 
Corrente
What’s the difference between 9/11 and a cow?
Submitted by lambert on Sat, 02/16/2008 - 5:19pm
Wait for it…
 
The Republicans don’t know how to milk a cow.
 
NOTE Saw something like this somewhere in my travels today, and if I remembered where, I’d give the hat tip.
   
cognitive dissent
“myths” and “facts” in the FISA debate
By cognitivedissident on February 16, 2008 6:54 PM
(...)
In a similarly humorous vein, lambert at Corrente http://www.correntewire.com/whats_the_difference_between_9_11_and_a_cow has my Quote of the Day:
 
What’s the difference between 9/11 and a cow?
The Republicans don’t know how to milk a cow.
 
It’s funny because it’s true; in another sense it’s not funny at all.
 
Yahoo! Answers
August 3, 2008
What’s the difference between a cow and 9/11?
george bush doesn’t know how to milk a cow
   
Twitter
Rod Flo
‏@RodolfoRamosJr
What’s the difference between 9/11 and a cow?
Americans don’t know how to milk a cow!
5:59 AM - 29 Apr 2009
 
Twitter
supercujo
‏@supercujo
What’s the difference between 9/11 and a cow? You can’t milk a cow continuously for 8 years.
5:57 PM - 19 Nov 2009
 
Twitter
Cero Mercer
‏@CeroBlade
What’s the difference between 9/11 and a cow?
You can’t milk a cow for 8 years.
4:14 AM - 20 Nov 2009
 
reddit
What’s the difference between 9/11 and a cow? (self.funny)
submitted September 2, 2011 by Froogler
You stop milking a cow after 10 years.
   
Google Groups: talk.religion.bahai
Satanic AmeriKKKan atrocity in Iraq in 2006: Mahmoudiyah killings & the rape & murder of Abeer Qasim Hamza
NUR
9/10/11
What’s the difference between 9/11 and a cow? You can’t milk a cow for 10 years.
 
Twitter
˹#lastAtheist™˼
‏@lastAtheist
~“What’s the difference between 9/11 and a cow? You can’t milk a cow for 10 years.” ~via comments: http://www.guardian.co.uk/world/2011/sep/10/911-religion-september-11 …
—parunach1
7:02 PM - 13 Sep 2011
Altadena, CA
 
Twitter
Jeff
‏@jeff_h0ch
The difference between a cow and 9/11 is that you can’t milk a cow for eleven years
7:19 PM - 11 Sep 2012
 
Twitter
drob
‏@dailydoseofD1
Whats the difference between 9/11 and a cow? You can’t milk a cow for 12 years. #justsayin
11:08 PM - 11 Sep 2013
 
Twitter
K∆IREL
‏@IllicitScript
What’s the difference between 9/11 and a cow? You can’t milk a cow for 13 years
7:48 PM - 11 Sep 2014
 
Twitter
Boris for PM ✌
‏@GenBrant
What’s the difference between a cow and 9/11? The US can’t milk a cow for 14 years
6:51 AM - 12 Sep 2015
 
YouTube
Jokes - What’s the difference between 9/11 and a cow? You can’t milk a cow for over 10 years.
jokesus
Published on Oct 5, 2015
Joke :
What’s the difference between 9/11 and a cow?
You can’t milk a cow for over 10 years.
 
reddit
What’s the difference between 9/11 and a cow?(self)NSFW
submitted January 25, 2016 by justsometurtleguyRETARD
America can’t milk a cow for 14 years
 
reddit
What’s the difference between a cow and 9/11?
submitted June 4, 2016 by xjqz
America can’t milk a cow for 15 years
 
Twitter
sad dad
‏@spookywitches
What’s the difference between 9/11 and a cow? America can’t milk a cow for 15 years.
8:22 AM - 20 Jun 2016