Dead Fish In The Ceiling
Remove the ceiling tiles and place dead fish up there. Eventually, over time it will begin to stink really really bad.

Icy Hot On Toilet
Spread a thin layer of Icy hot on the toilet seat in the restroom. This prank can also work by applying some to the toilet paper. After doing this, the next person to use the toilet or paper will get an unexpected burning sensation.

Keyboard Switch-a-roo
While in the computer lab, when the classmate next to you gets up to use the restroom or whatever, unplug his keyboard. Then plug your keyboard in to his computer. When he gets back, start typing thing for him...start with, "Hey, Welcome Back"

Glue And Pens
If you have time you can glue all the pens in your classroom so the lids cannot come off.

Itching Powder On The Toilets
During class while everyone is learning. Ask to be excused, go to the restroom and leave itching powder all over the toilet seat and on the toilet paper.

Mouse Swap
While in the computer lab, ask the student next to you if you can borrow a pen. While he is digging for one in his backpack, quickly switch his mouse with your mouse. So when you gets back to his computer and tries to use his mouse...you will have total control over his computer.

Apple Juice Piss Prank
Always have a bottle of apple juice handy in case a classmate falls asleep in class. When he does, pour a little on his pants, the seat, or even on the floor below him. When he awakes he will think he pissed his pants.

Saran Wrap Car Doors
Go to the student parking lot during class and saran wrap cars so the doors cannot open.

Granny Style Underwear
Go to the store and buy the biggest granny style underwear you can. Smear some chocolate on the back side of the underwear. Then place them in the middle of the hall before school begins.

Super Glue The Water Fountain
Have some super glue handy, next time your victim is thirsty and needs to get a drink of water at the water fountain. All you have to do is jump in line in front of him, then quickly squirt a couple drops of super glue on the button. When its his turn next, his finger will be stuck.