Anything you do to their Jeep will be vandalism at the least. Is revenge worth a felony...........
On the other hand, shove a key in the ignition and break it off. Pop the hood and take the air filter out. Put water in the oil fill. Break the windshield. Sugar or salt in the tank. Dump rit die on the seats. Pee on the carpet. Egg it....eggs will take the paint off. Key the paint. Slash the tires. Cover the Jeep in maxi pads (my favorite cuz it doesnt hurt it, but everyone sees it). Loosen the lug nuts. Cut the brake lines. Hide dead fish under the seats or carpet. Fill it with road kill.
do you need any more ideas