Ever want to play a practical joke on a friend? Leave your phone laying somewhere for someone to pick up: they will happily play along pressing the kind button until shrieks erupt right in their face! (Hilarious to watch!) You will immediately know that someone is using your phone when you don't wan them to!
Freak out your friends with a 'friendly' little app displaying an enticing button to click! When they click it, an alarm will ring through the entire room letting you know somebody has tried to use your phone!