Jokes about the September 11, 2001 terrorist attacks on New York City’s World Trade Center are numerous, although not politically correct. One popular joke is:
 
“9/11 jokes aren’t funny. They’re just plane wrong.”
 
“Jokes about 9/11 are just plane wrong” was cited on Twitter on September 11, 2010. The joke has been printed on several images.
 
“9/11 jokes aren’t funny. But the other 2 are” is another 9/11 joke.
     
 
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 Tuesday, September 11, 2001. The attacks consisted of suicide attacks used to target symbolic U.S. landmarks.
 
Four passenger airliners—which all departed from airports on the U.S. East Coast bound for California—were hijacked by 19 al-Qaeda terrorists to be flown into buildings. 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.
 
Twitter
Brandon Barker
‏@brandonbarkerzn
9/11… I would make a joke about this, but that’s just plane wrong.
7:07 PM - 10 Sep 2010
 
Twitter
Steve
‏@UB7_Steve
9/11 jokes today are just plane wrong and could get you into lots of rubble
4:38 AM - 11 Sep 2010
 
Twitter
Nitin
‏@nitinbhat
Jokes about 9/11 are just plane wrong.
9:25 AM - 11 Sep 2010
 
Twitter
emily rose
‏@ilovetacobell
“9/11 jokes aren’t funny.” “thats just plane wrong”
12:07 PM - 25 Apr 2011
 
Twitter
Sarah Willis
‏@sarahashley621
“9/11 jokes aren’t funny.. they’re just plane wrong.”
3:06 PM - 25 Apr 2011
 
Twitter
clare lyons
‏@static_prevails
9/11 jokes aren’t funny…. they’re plane wrong. omg i can’t
4:06 PM - 25 Apr 2011
     
Google Books
This Is Why We Can’t Have Nice Things:
Mapping the Relationship between Online Trolling and Mainstream Culture
By Whitney Phillips
Cambridge, MA: The MIT Press
2015
Pg. 117:
... deliberately bad wordplay (“9/11 jokes are just ‘plane’ wrong”; “9/11 Americans won’t understand this joke”), ...