Step One: Create a deeply twisted and emotionally disturbed character possessing one individual character flaw or psychosis exhibited by each of your classmates. Become accustomed to roleplaying that character.

Step Two: Write each of these character traits on an ordered list beginning with the individuals you dislike the most. Make many copies.

Step Three: Acquire a paintball gun. Place your ammunition in the freezer. Be sure it is red.

Step Four: Blindfold your classmates and bring them out into the woods to a predetermined location. Choose an area you know well.

Step Five: Give each of them a copy of the list. Allow each classmate one guess at which one trait from the list belongs to who. Only one each. For each correct answer add the corresponding trait to your own personality.

Step Six: By now everyone will be to busy feuding over who accused who of what to have bothered to notice your gun. This is where you really need to have your character down pat. Each classmate with a correct answer gets a ten second head start. Everyone else is screwed. Shreik with the joy of all their combined insanities and open fire.

Perfect for a psychology class. Simple, traumatising, and educational.