This is quite a 'famous'/'infamous' photo resulting from 9/11.
One inevitable byproduct of a disaster as enormous and devastating as the September 11, 2001 terrorist attack on U.S. soil is the dissemination of sick jokes referencing the event. The so-called "Tourist Guy," pictured above, was one of the first clear-cut examples of a joke pertaining to the events of 9/11. Both the image and the accompanying text (in all its different versions) are fake.
If you look closely at the above image, Midtown Manhattan is discernible in the background behind the blissfully unaware subject, indicating that the photographer was facing north from the location of the Twin Towers at the moment the photo was snapped. Only one of the airliners that collided with the World Trade Center on September 11 approached from that direction - the first, American Airlines Flight #11, which struck the north tower (One World Trade) at 8:45 a.m. The trouble is, the north tower had no rooftop observation deck like the one pictured here. Even if it had, it wouldn't have been open to tourists at such an early hour.
There are additional discrepancies to ponder:
Why isn't the fast-moving aircraft blurry in the photo?
Why doesn't the subject (or the photographer, for that matter) seem cognizant of the plane's high-decibel approach?
The temperature was between 65 and 70 degrees that morning, according to news reports. Why is this man dressed for winter?
How did the camera survive the 110-story fall when the tower collapsed?
How was the camera found so quickly amidst all the rubble?
Why did this one-of-a-kind, newsworthy photo never appear in the media until after it had already been well circulated via email?
As to the question of why anyone would invent a hoax as callous and tasteless as this in the first place, I would simply point out that the emergence of sick jokes is more often the rule than the exception in the wake of tragic events such as 9/11. Much as we may not like to accept it, the behavior is both predictable and understandable in terms of how people cope with the unthinkable.
To borrow an observation from folklorist Alan Dundes, the example before us demonstrates that "one person's tragedy may become a point of projection or catharsis for the fears and anxieties of others. Remember, people joke about only what is most serious."
It doesn't get much more serious than this.