I want to be funny in my speech, but.....?

Okay, so if you've seen my other question you know I'm running for 8th grade class president against the most popular girl in our school.....and I'm not popular. But here's the thing. Two people suggested I use humor in my speech. I've always been funny around people, but when making a speech in front of hundreds of people in the 6th, 7th, and 8th grade plus all of the teachers, it makes me kinda anxious. Could somebody suggest some jokes I could use and how to become less nervous about presenting? Thanks very much!