I'd get a turbo timer - if you have the key in the ignition then they can walk up - smash a window - unlock the car and drive off. if you have a turbo timer you can set it to run for 10 mins - if someone gets in and touches the foot brake/hand brake it'll shut the car off.
haha beaten to it! bit more info here... http://store.mp3car.com/Mimics_s/353.htm dunno why your mate doesnt like people knowing how his done it.. sharing is caring!
Before telling such sick and abusive jokes about Amy Winehouse, think about her poor close friends, imagine how they will feel on Tuesday when they wake up and find out.