Here's a quick how-to that shows you how to modify a single use camera so that it shocks the person when they press the shutter button. The video includes a bunch of clips of unwitting suckers using the camera.
UPDATE: let it be known that I consider shocking someone to be a crappy, unfunny prank. Link
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. His new book is Maker Dad: Lunch Box Guitars, Antigravity Jars, and 22 Other Incredibly Cool Father-Daughter DIY Projects