Humor happens when there is a discontinuity in the narrative line.

Imagine with me... Story-space.
All stories, all narratives, all jokes trace a line in story-space, some are parallel,  they travel in all directions.

When the narrative line is discontinuous, either by making a sharp turn or by making a jump or both, there is potential humor and it's funny when the listener makes the jump with the teller. The bigger the jump, the sharper the turn, the funnier. Right up to the point when the listener can't make the jump. Then it's not funny.

What did the refrigerator say to the chair?
Dick Tracy.

Too big a discontinuity. Not funny.


A man walks to the park.
He sits on a bench.

No discontinuity. Not funny.


A priest, a rabbi, and a minister walk into a bar.
The bartender looks up and says, "What IS this? Some kind of a joke?"

Several discontinuities. Funny for those that make the jumps.


Most objects have an implied narrative line. When they get used for something else, that's a discontinuity.
It's the basis for the charm of sculptures of animals made out of recognizable farm implements.

When something makes you laugh or even just chuckle, if you look for it, you can find the the discontinuity in the narrative line. It'll be there.