I have heard first hand story's of 9/11 celebrations that happend in Stockton Ca from a friend who live across from people that were Celebrating!
I have also heard other story's of it, So I go to snope's to see what they have to say.
And What do you know Snope's say's "UNDETERMINED" Here is a link http://www.snopes.com/rumors/photos/shirt.asp
Then you can Google it Lots of story's and news about the Issue. Even You Tube.
But Snope's cant seem to come up with the fact's
Does this Shirt Exist ???? and Who cares if it does or not. Does the "Religion of Peace" celebrate 9/11 HELL YES.