Today, Click and Clack, the car guys, offered a great practical joke that goes along with what you've just said.
Fellow's friend bought a new car and couldn't stop bragging about how great it was. Fellow wanted to shut friend up before he became an enemy.
C&C suggested the following: head for the junk yard or carparts store. Scoop up a few handfulls of odds and ends, the odder the better. Each time the friend parks his car, sprinkle a few of the bits under the car, preferrably where he can see them. Also, crawl under the car and attach some of the bits in such a way that they will rattle when the car is moving, and periodically some piece will fall off and be visible on the road in the rearview mirrors.
Finally, purchase some red fruit punch, and pour a bit of it on the ground under the front of the vehicle, such that he will see it when he comes out to start the car.
Eventually, cease this silliness, preferrably before the friend either goes insane or finds out it was you.
maxine in ri