Wouldn't even tingle. The human body doesn't have enough potential to generate a shock from a car battery. I have to teach my help that all the time. I tell them, they look at me like I'm an idiot, I reach over and grab both terminals on the battery and show them.
You need something to step the voltage up, way up, like a coil or a capacitor to be effective. Even then, you would need to generate a circuit path, one leg to the door, the other to ground. If the ground is dry and they have rubber soled shoes, you need a lot more voltage. Iffen I was going to do it, I'd get the electric fence charger that has the picture of the upside down fried cow on it.