This is actually a helpful rescue tip! But, in the wrong hands, it could be considered as a warning. Because, if you can do it, a criminal could do it.
You can actually open a car door, that uses an electronic key entry, using a tennis ball with a hole cut in it. The hole must be shaped about the size of your key hole. By placing the tennis ball hole over the key hole, and applying rapid pressure (by squeezing the ball as hard as you can), the air flow can unluck the car door lock.