Trick for locking your keys in the car
If you find yourself in the akward place of your keys being inside your car and you on the outside while the doors are locked.
If you have an extra car remote at home (and someone there to call). Give them a call with your cell phone and have them press the remote into the receiver while you hold the phone towards the car. The signal will unlock the car door.
Trust me, it works. I have helped many people out of a jam this way.