A free app for Android, by stick hunter.

The Timer Bomb Prank is a prank app that lets you place an explosive device on your phone screen and explode it at a predetermined time. The app has various options for you to choose from, such as the type of device, the amount of explosive, the timing of the explosion, etc. Once you have set the timer, you will be able to place the device on your phone screen and press the button that will start the countdown. When the timer reaches zero, the explosion will blast and the screen will break into pieces.

You can also select the location of the bomb on your phone screen and the amount of explosive you want to use.