Earlier today I was watching Curb Your Enthusiasm (if you haven't heard of it then WATCH IT). So, while I was watching it I was just jotting down funny lines. I will sometimes pause it and write out WHY that line is funny and WHAT makes it funny. On some of the jokes I write down I will go through an entire WHO, WHAT, WHEN, WHERE, WHY, HOW scenario.
This is interesting to do with Curb, because it's not exactly set up/punchline jokes. This is because it's not even a scripted show. Each episode just has a rather detailed outline and the actors improvise from there - much like how Reno: 911 was.
In the pilot there is an ongoing joke about how Larry David called this woman CaroLIN, but her name was CaroLINE (Caroline) and she ends up getting very upset about it and Larry thinks it's not a big deal.
WHO - Larry David and a woman he just met
WHAT - The joke is that Larry pronounced this woman's name wrong and she really overreacted about it.
WHEN - I see the when as "when does the joke come up during the episode." It is an ongoing joke, so it comes up on multiple occasion's as she makes an even bigger deal about it once she confronts Larry.
WHERE - The joke first happened during a short "I just wanted to say hello" moment between Larry and Caroline.
WHY - Simply because it is a relatable situation that breaths comedy.
The HOW doesn't really relate to this.
I'm a firm believer in breaking jokes down to see what makes them funny. It's astounding what you can learn about comedy in doing this.