You should not attempt these things during an actual exam. The following is meant for entertainment purposes only.
1. Bring a pillow. Fall asleep (or pretend to) until the last 15 minutes. Wake up, say "oh geez, better get cracking" and do some gibberish work. Turn it in a few minutes early.
2. Get a copy of the exam, run out screaming "Andre, Andre, I've got the secret documents!!"
3. If it is a math/science exam, answer in essay form. If it is long answer/essay form, answer with numbers and symbols. Be creative. Use the integral symbol.
4. Make paper airplanes out of the exam. Aim them at the instructor's left nostril.
5. Talk the entire way through the exam. Read questions aloud, debate your answers with yourself out loud. If asked to stop, yell out, "I'm so sure you can hear me thinking. " Then start talking about what a jerk the instructor is.
6. Bring cheerleaders.
7. Walk in, get the exam, sit down. About five minutes into it, loudly say to the instructor, "I don't understand any of this. I've been to every lecture all semester long! What's the deal? And who are you? Where's the regular guy?"
8. Bring a Game Boy (or Game Gear, etc. . . ). Play with the volume at max level.
9. On the answer sheet (book, whatever) find a new, interesting way to refuse to answer every question. For example: I refuse to answer this question on the grounds that it conflicts with my religious beliefs. Be creative.
10. Bring pets.