So the prank starts where you find a resturant or some store that serves food. Walk in wearing Haz mat suits and holding gieger counter. Rig the gieger counter so there is a hidden button to make the thing start clicking. Go around the resturant and make it click when its near food that is on peoples table. At this point you can either leave it as it is and ask to speak to the manager or you can make it click crazily next to someone that seems to be enjoying there food a lot. When it clicks more than it has before shout and scream to each other and sprint out of the building.