I look at my childhood art now and see that I was, indeed, always telling stories through my art. The art is very narrative. But I didn't. It was there all the time. Humor is incorporated into your books, and a lot of people think this is the hardest thing to do.
Unexpected things are funny.
Surprises make people laugh. Opposites are funny. Exaggeration is really funny. Unexpected things can feel disconnected. In other words, there IS no formula to writing humor.