Some pranks are just too good and this one for your phone would cause you to panic slightly because once downloaded and run this app takes over your screen and turns your volume up to max. It plays audio of my choosing and of course I've made it as embarrassing as possible for you. You wouldn't want people around you when this is run because you won't be able to stop it.
It hijacks your screen and that home button, only turning the device off will stop it.
And the whole time you'll be looking at my photo, how sweet..