Excerpt from Mathematics and Humor:  Freud Would Be Proud  by Jerry Johnson;  Hold That Thought Publishing, 2020
World’s Funniest Joke
In the early 2000’s, British psychologist Richard Wiseman and his colleagues at the University of Hertfordshire conducted a long research study called “LaughLab.”  Their study tried to measure the humor in jokes using a five-point ‘glggleometer,” in addition to MRI scans that identified the brain’s laugh center as being a region near the back of the frontal lobes.
Bases on Wiseman’s research, one joke stood about above all the rest:

Two hunters are out in the woods when one of them collapses.  He doesn’t seem to be breathing and his eyes are glazed.  The other guy whips out his cell phone and calls the emergency services.  He gasps: “My friend is dead!  What can I do?”  The operator says: “Calm down, I can help.  First, let’s make sure he’s dead.”  There is a silence, then a shot is heard.  Back on the phone, the guy says: “OK, now what?”  

[Newscientist.com (October 3, 2002)]