I saw something where a person gets a message on their phone that says your contact list will be erased in 10, 9, 8... and there is a countdown.
I think it would be funny to have an app like that where it can say something like all of your information will be erased in 10, 9, 8.... Even better if once the countdown got to zero the phone actually rebooted itself to scare the person even more.
I would love to have it customizable so you could put anything you wanted, like you phone will dial 911 in 10, 9, 8...
and what point would this app serve? you'd have to have the trust of the person just to get your hands on the phone, then have to keep them preoccupied with something else while you searched for and downloaded it. then you would have to get them to unknowingly click on it.
the work involved would far outweigh the humor I'm sure only YOU would find.
now... if there was a SMS/MMS you could send that would cause the same sort of thing, THAT would be better. However, could you imagine the reaming you would get from that person once they realize it was a joke??? And, even more so, what happens when someone creates an app or whatever that actually DOES erase it, and the people you send it to use it thinking that you were just trying to be funny again???
I was uncertain how the app would work but I am assuming it would be by email or text, you are correct that an app on that persons phone would make the practical joke less effective.
Now in regards to the idea, the whole point is because it is a practical joke. There are so many practical joke apps on the market, and they are intended to be for fun.
I think the reaction from the person would be priceless, and if someone were to create an app that wipes the whole phone for real, well I hope it nevers finds my storm.