I still have to try this.
Locked your keys in your car ? Did you know this? Good thing to know. If
you lock your keys in the car and the spare keys are at home, call
someone on your (or someone else's) cell phone.
Hold your cell phone about a foot from your car's front windshield, or
dash and have the other person at your home press the unlock button of
your key fob (clicker), holding it near the phone on their end. Your car
doors will unlock. It saves someone from having to drive your keys to
you.
Distance is no object you could be hundreds of miles away, and if you
can reach someone who has the other "remote" for your car, you can
unlock the doors (or the trunk!).