Does your school have nylon carpets? Do you have shoes? If the answer to both these questions is yes, then you have the basic ingredients for a static attack.

1) Shuffle around on the carpet for a while, keeping both feet on the floor at all times.
2) Approach victim. Preferably someone who hasn't been watching you shuffling around. Keep feet on floor as per stage 1.
3) Touch victim on earlobe or neck. Listen for sharp 'crack' and smell the sound of electricity and burning hair as your victim writhes on the ground in agony with smoke coming out of their ears.

In reality, stage 3 will be a disappointing "Ow!", but it does hurt. A bit.

More advanced static attacks can involve jumping off the ground and touching the victim in mid-air. Tests to determine whether this increases the amount of pain experienced by the victim have so far proved inconclusive.

The electrical capacitance of the average kid has yet to be accurately calculated, leading to the theory that if you shuffle around on your feet for an entire lunchtime, you will store up enough power to cause your victim to explode. Early experiments suggest that this theory could be fundamentally flawed, but further developments are eagerly awaited.

To make the ultimate static attack, you need to apply a straightened out paperclip onto your victim's teeth after getting your charge up.
You're all wrong, I'm afraid. The most eye-watering static attack is executed by lightly touching the tip of your victim's nose. Go on, try it. - Ponky