Getting traffic for a joke site works very well with viral techniques. Here is a technique............. Write a very funny storey and put a link back into your website at the end of storey as, Abstraction form "yoursite.com" Next, mail it to your friends........... Really, this technique will give you more successful results because funny things always become viral. How it becomes viral? People always like to share funny things with others. So, your friends will send it to their friends, and those friends will be sharing it with their friends................................
I agree with digitmar. Viral marketing is the way to go. If you have a lot of friends on Facebook then this will work really well.
Search google for joke forums and post comments and be a part of the community... of course, use your url as anchor text in your sig