They say that deconstructing humor is like watching sausage being made. I don't agree with that, because at the end of the day, deconstructed humor isn't edible.
I'm taking a class on sound design, about how to record and edit decent audio. The instructor mentioned that he had some audio samples of Brian Eno and we were going to practice listening closely.
"Pardon?" one student asked. "You should listen more closely," I said. I was surprised how much everyone laughed at that. It was such an obvious thing to say. I remember waiting half a second for someone else to preempt me.
I've thought a lot about what makes people laugh. There's a large variety of distinct things that people laugh at, but one of the most common is when you make a logical conclusion that is completely ridiculous. For example, let's say Joe the plumber sees the Oscar Mayer Wienermobile driving down the street. Joe asks, do you think they use cooking oil in there instead of motor oil?
That's not particularly funny but that's off the top of my head. You see, cars have oil in them, food is cooked in oil, so it makes sense for a giant hotdog car to have cooking oil in its engine. It's logic followed to a point of absurdity.
Months ago, I was presenting a story about a professional blogger who, when the power goes out, devolves into a caveman-like state, but still must find a way to make coffee. The instructor casually and humorously mentioned that it would make a great commercial for Foldgers. Then a fellow student presented an abstract story about a woman who, when full of loneliness, falls in love with her furniture and eventually becomes a chair, literally transmogrifying. I said that it would make a great commercial for Ikea.
The humor there was in the repetition of a pre-established notion, again drawn out to a logical discordant extreme. Without the preexisting idea of stories-as-advertisements established by the instructor when I pitched my story, my comment would then just be weak semi-relevant sarcasm. The Ikea comment is only funny when the logical idea already exists but is followed illogically in a logical direction. Like a flea circus.
Those sorts of jokes must make complete sense but must be completely absurd. Of course, there's no time in normal conversation to construct a joke. You simply speak and hope the words you're saying aren't too dumb.