My brother worked at a movie theater when he was 16. One night, he decided to play a prank on his boss. He and I jacked up his boss's car and put jackstands under the drive axle. We lowered the jacks so that from a distance, the car appeared to be sitting on the ground. His boss came out with the night deposit to go to the bank, started the car and put it in reverse; naturally, the wheels just spun as he tried to drive away. He, assuming that the transmission was messed up, went back inside with the deposit to get another employee who was good with cars. While he was inside, we quickly removed the jackstands. Of course, when the employee came out, he put the car in reverse and it worked just fine. The boss, looking perplexed went back inside to get the deposit, and while he was doing that, we replaced the jackstands. This time, when he put the car in reverse and it wouldn't move, he just kept reving the engine. He was quite angry and began slamming things around inside his car. The movement he was making was enough to slip the car off of one of the jackstands and, since he was reving the engine, sent his little car, tires screeching out of the parking space and into the aisle. Fortunately, he dodn't hit anyone or anything, but we decided that we wouldn't reveal ourselves since he was more than a little put out! We decided that the lost jackstands were worth the cost of a pretty good time, and we left them, and my brother's boss in the parking lot.