Locking you keys inside your car has to be the worst feeling in the world. You feel stupid, powerless and you can see them right through the window (which you really don’t want to break).
 
Before you panic or call a locksmith, grab a tennis ball. We’re not kidding.
 
Just take the ball and make a small hole in it, best done with a hot screwdriver. Hold the ball up to the car lock with the hole facing the lock. Then, press the ball against the car as hard as you can.
 
The air pressure will open the locking mechanism.