if you want to be mean my favorite is taking off the lug-nutts fill them full of jb-quick put them back on but only thread them down about half way so they are all about a half an inch from touching the rim. i promise you they will not come off. every studd on the car will have to be broken off and replaced. Befroe you leave make sure to cut the sidewalls in the tires so they cant drive it and when they go to change the tires they will find the messed up lug nit and have to call a flat bed to come pick it up.
NO bad advice. PIIHB j/k seriously ask her out, if she says no. then slip her a roofie and......never mind thats gonna be bad advice to.
my friend once wiped his own **** onmy side mirror to my old buick. Me and some buddies had him run an errand with another friend to pick up some blunt wraps at like 1 and when he was gone we seran wrapped over his mustang's doors over and under the whole car a good 2 layers, then we drew a huge spermin penis on his hood with ketchup and used aluminum foil to "chrome" his wheels, his wing, side mirrors and some other stuff. He was pissed and he punched through the seran wrap and jumped in the car and just took off, all of the crap going all over my street. We then had to pick everything up and rinse his car. it was funny though.
Go to home depot and look in their moving section. Get one of those rolls of plastic film they sell for wrapping cabinets, dressers etc. They are used to keep the drawers, doors etc from opening in transit. Catch her with her back turned and wrap her whole car. Here's the trick. Do it at night and put something slippery over the door handles, then sit back and watch. At first she won't know what the hell is going on, she'll keep trying to open the car door and her hand will slide right off of the slippery plastic film. She'll look like a tenth grader on prom night looking for his girlfriend's g-spot. The plastic film is thin and she can tear it off with relative ease, and it won't damage the paint. I saw some guys to this to a guy's car one night, he went into a bar and got drunk and when he came out he didn't know what the hell was going on. He fumbled with the handles for minutes before he figured out something was wrong. Hilarious.