SCOTT ADAMS of Dilbert fame lists the 2-6 rule for humor. There are 6 items that bring humor and you must engage at least 2 of them for a comic strip to be funny. Read the WHOLE ENCHIRTO WITH HOT SAUCE.
I wrote on this topic more extensively in my book, The Joy of Work. So I’ll just give you the highlights here. The core of humor is what I call the 2-of-6 rule. In order for something to be funny, you need at least two of the following elements:
Cute (as in kids and animals)
Recognizable (You’ve been there)