Place your device in a mischievous fart location, such as in your back pocket, next to your butt or under granny's chair and tap the red button to start the farts. It will be like granny is breaking wind.
Or install on your friend's device than tap the Hide button to start the farts in class.
If the fart sounds are too frequent or if there are an insufficient amount of smelly fart noises for your prank, the frequency of the stinky flatulence can be adjusted on the settings menu.
The fart sounds have been digitally remastered for maximum smelly fart clarity.... It's like they're coming from your bum and you can almost smell them.
There are a variety of trump and flatulent sounds, the joke possibilities are endless.