Do The Roar, will allow anyone to annoy Shrek, and cause him to bellow out his enormous Ogre roar. Use Butterpants to help you annoy Shrek, just keep punching the button, or shaking your phone, and the little boy will badger the big ogre. Finally, Shrek will let loose with his famous roar. Be careful, you may need to clean your phone afterward.

http://appshopper.com/games/do-the-roar