To prepare members for the coming humourous speech contest, I recommend you to take a look at these two sites.
http://artofspeaking.org/
Watch videos of funny speakers in action, learn a trick from them and win the contest! Here is one I thought it's so funny.
http://www.artofspeaking.org-a.googlepages.com/powerpoint-funny
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This site provides additional materials for you to learn how to be humourous.
The Art of Using Humor in Public Speaking
by Anthony L. Audrieth
http://www.squaresail.com/auh.html
Cheers
GOh Kheng CHuan