Reminds me of a situation I once found myself in.
See, you need to know that both me and my friend NEVER lock ourselves out. We're very good about it. Furthermore, BOTH of us usually keep two copies of our car keys on our person at all times...one on a keychain with the house keys, and a separate key by itself that we use to actually drive the car.
Anyway, this was the rare day when I hadn't gotten the other key for my car, so I only had the one copy. I drove to where I was going, locked the door and closed it...just as my hand brushed my empty pocket.
I looked in the window of the car, to see my keys dangling from the ignition. CRAP. I called my friend, and got him to bring me the copy that I USUALLY carried with me. He gave me tons of flack about it for the rest of the night.
Later on the same day, he was at his girlfriends' house, while I was watching a movie. Suddenly the phone rings. It's my friend, who says "you're not going to believe this..."
I got his keys from the dresser, and drove over to unlock his car.