Here are the best ones from:
51. Sugar not in the Gas Tank
Just sprinkle some sugar around the gas tank opening. For added confusion leave a note with somebody else's name. "Ha ha Steve that will teach you to cut me off in traffic!" No damage happens with this prank.
52. The Accident That Didn't Happen Prank
Leave a note on somebody's windshield, "Sorry I smashed into your car. I have gone to the hospital to get my injuries checked out. Call me and we can work out a cash settlement-I don't have any money but maybe I could trade some yard work or something to pay it off. Call me."
55. Flat Tire Prank
Take some regular balloons and fill them up. Place under the tires so that when the car moves they think they have a major problem. Works best at night. Try to keep them out of site.
62. The Fake Company Prank
Make up a sign for a fake company like - Wash your toilets by hand, Inner thigh massages or something to that effect. Put the sign on the passenger side of the car. If you pick the right opportunity they will never know it is there.
79. Car For Sale
Put a for sale sign on somebody's car. Include phone number and an extremely ridiculous price. Works well while they are on vacation - should be plenty of messages when they get home.
And another one (different site):
I got this from a Calvin and Hobbs comic. Get up early in the morning on a snow day and build three snowmen make two of them right in front of your dads car and have there arms pointing upwards and have there faces look shocked (example, use charcoal to make a big circle for the mouth so it looks like there screaming) the third snowman should NOT be put together but instead have its bottom section halfway under the car its middle section on the hood and its head near the windshield make little "x"s for eyes using sticks so it looks like he got hit by the car. Make sure its a work day because then your dad will have to clear it away to get out to go to work