this is a quick annoying prank easily transferable and reusable.
Step 1: Materials
You will need a mercury switch and an alarm siren, and a cigarette lighter plug.
Mount the siren and mercury switch to a peice of wood or plastic to keep it stable.
Wire the siren to the cigarette plug, with the mercury switch in line.
Plug in your gadget to a power port and adjust the mercury switch so that it will make contact as soon as any quick motion occurs.
Now wait for someone to move the car.
Step 2: Finished Product
this will be