I am sure that there are plenty of my fellow geeks out there who do love a good practical joke. Well, if you happen to be one of those people check out the photo below for what could be one of the greatest practical jokes I have seen in a long time.
All you need is a an air horn which you tape on the wall behind a door. Then when your unwitting subject opens the door the door handle will press the air horn and give the fright of their life. You can buy Air Horns from Amazon. Well worth the money.