I’ve yet to see a mention of a practical joke that can be played with an iPhone. So let me be the first to offer one-albeit one that will only momentarily confuse your victim*.
Download this image, gain access to your victim’s iPhone, and sync the image to their Photo library. (No, I can’t be bothered with details such as how you’re going to wrest the phone away from this person or how you’re going to sync it without wiping out all the media on the phone. Do I have to think of everything around here!?)
Select this image in the iPhone’s Photo application and let the phone slip into standby. Watch with delight when your victim picks up the phone and taps repeatedly (and impotently) on the display.
* Or not. Consider this an intelligence test. The second your victim taps the screen, the Photo application’s navigation controls will appear. If it takes more than 10 seconds for this person to understand they’re tapping on a picture of the interface rather than the interface itself, maybe they shouldn’t be trusted with such an expensive device.
Practical Joke #2:
...or, sync a cropped photo of the golfing victim's iPhone screen (from the next story below).
That way your friend will freak out thinking thier screen is smashed. :0)
'kito
Try putting the picture upside-down and really freak them out.
The first practical joke I heard was to bring up a picture that is purposely oriented 90 degrees from the correct orientation. Person tilts iPhone to see photo the right way, and photo immediately rotates another 90 degrees. Could be maddening.