This is why I'm glad I spent the money on my alarm time and time again.
Ok, you're getting food and some ****ing retard decides your car is probably better than his and gets jealous. One of two things may happen.
1. He sees a little LED blinking in your dash and decides not to screw with your car
2. He breaks your mirror, your alarm sounds, you run out and beat his ass down then have him pay for it.