Who are the fastest readers? 9/11 victims. They went through 89 stories in seven seconds.
I think it's pretty morbid to talk about terrorism in that way. Why aren't you being more compassionate towards those victims of the 9/11 attacks?
Do you even know who those victims of 9/11 are, or are you just being malicious? It's a conspiracy theory that the people in the towers were killed by their own government.
Making light of the deaths involved in the September 11 attacks on the World Trade Center is inappropriate since it trivializes the loss of life due to terrorism. Many families have been impacted by loss due to 9/11 and making light of what happened makes it more difficult for them to  accept what happened and psychologically recover. Instead of joking about morbid things like 9/11, why not be more positive and joke about more lighthearted things so that you don't offend anyone?