PopOff displays nine pre-recorded sound effects on the screen at any given time, though there are more than that available. You can shake or tap refresh to receive a new menu of sounds. Sound bytes range from animal sounds to short one-liners.
PopOff's big claim to fame is that users have the ability to use the iPhone's built in microphone to record and name their own sounds, which is where most of the fun stems from. If pre-recorded sound effects like pigs and air horns don't do it for you, you can make your own. Your recorded sound effects can also be set free for the listening pleasure of other PopOff users.