An instant later they find themselves in the afterlife, being judged by Almighty God Himself.
One falls to his knees, "I deplore you, all-powerful Creator of the universe! Before you judge me, I humbly beg you, reveal who was behind the September 11 attacks!"
God sighs. "Muslim extremists. Al-Qaeda and Osama bin Laden did it."
His friend leans down and whispers, "Damn, dude. This thing goes way higher up than we ever realized."
E: If you think the joke is funny you should see all the butthurt 9/11 conspiracy theorists in the comments