A lot of people will tell you that there are no shortcuts to success and for the most part they are right.
However, for those of you out there that still have that burning desire to learn how to be funny then the "pull back and reveal" technique is about as close as you can get to having a tool you can use to bring out laughs almost instantly.
What is the "Pull Back and Reveal"? In a nutshell it is when you start a joke or funny story by focusing on a smaller aspect or detail of the situation.
Then you pullback the curtain and reveal to your audience the whole picture.
This technique is all about surprise and timing.
Here are some other points worth noting:

• What you are "revealing" is a missing piece of information.
  
• Usually the missing information is something that is very obvious or naturally assumed.
  
• You want to be careful not to give away the one fact which makes the surprise.
  
• Its best to start with a very short, descriptive situation that has within it an element of predictability.
   Ask yourself, "What is automatically assumed in this situation?"
• Keep it short.
   Its best to be brutally brief! (Now say that 10 times fast).
  

Let's do a break down of the pullback-and-reveal in an example.
 Take the following joke: "My girlfriend called to tell me she thinks she's pregnant.
"Great! I said,...
but are you ready for that?...
It can be tough being a single parent these days.
" The setup is worded in a way that leaves a wide range of predictable assumptions, including: 1.
       The person telling the joke is a man.
2.
       The child is his.
3.
       He will help take care of the child.
4.
       He really is happy about the news.
You can see how using assumption #3 from above leads us from pullback to reveal.
Hope this helps.