Pranks???

I have recently embarked in a prank war with a teacher of mine and this man is good. So I am looking for the ultimate prank that is harmless but still brutal in the same sence. If any one has any brilliant scemes that they have perfoomed or even have thought of I am taking request

knock up his wife

Dont knock her up but at least pee in her butt LOL
Go out to his car jack it up on the wheel that pulls put a block just tall enuff to keep tire from gripping then take jack out and leave, if he is like most teachers he'll be calling tow truck within minutes

If he sits in a fabric chair, put tabasco on it the night before and after it dries, when he sits, it will make his butt burn really bad. Or, you can freeze a can of shaving cream, cut it open and put it in his desk drawer, when it unfreezes, it will expand everywhere.

big ass zip tie on the drive shaft harmless but will sound like the motor is comin apart.they sell them at homedepot, industry calls em panduit straps

Hey I like James's idea...! First off is this college or high school? Just want to know your limits....

tape 2 ketchup packets under his toilet seat so when he sits down to take a terd they explode on the back of his legs...mayo works great too

Wire the horn into his left directional. Proven to be hilarious.

if you can get into his vehicle, what you do is pop the hood, run a wire from the distributer(sp), run it into the cab and have it poke through the seat where its seperated from back and bottom so its right @ his ass, proven hilarious, shocks the shit out of him everytime that cylinder fires

find a picture of him from when he was like a teenager, and photoshop it all 2 hell. and then make around 500 copies of it and pass em out around the skool, and put em all over his car w/ maskin tape.
not that ive ever done this or nething