What is the best way to get traffic to my joke site?

Optimise would be a good way.

Join into forums where they tell jokes........

 

Seo, links and directory submission is the best way to start..

 

posting on entertainment forums with link on sig with attractive anchor text (also keep changing the text frequently)

 

Jokes seem to do well on Stumble.
Build a network of friends there that will stumble and comment your jokes.
Careful not to over promote, you will get banned.
You will not get many clicks on your ads, but it's good exposure and if the jokes are good they'll get picked up by bloggers and get submitted to other social sites.

 

Try bookmarking sites , exchange links with othe related websites , And seo .