Plan your speech by starting with the basics: introduction, body and conclusion. Focus first on writing a good speech and then add humor.
Limit your speech to three minutes. Presenting a funny speech is like stand-up comedy -- brief yet punchy.
Craft your message first. Although the speech will be funny, deliver a positive and heartfelt message that will stick with your audience.
Find humorous situations such as running late, barely passing classes and losing your speech to help your audience relate to you. Stay out of personal circumstances that apply only to you.
Refer obliquely to a teacher that is a hard grader but never use her name. Don't single out individuals as a source of humor. No one likes to have jokes made about them. Use the reference only if everybody knows the teacher -- if it's already a joke.