Take a picture or a selfie and send it to a friend, or several. Their front-facing camera captures a "stealthie" of their reaction as they view it. They then have 5 seconds before the stealthie is sent back to you, unless they shake to retake or swipe right to quit the game.
You can keep playing and building up stealthies until one of you stops the game - at which point, all stealthies in that thread are deleted.
If the first stealthie that the app captures is just too bad, you can shake to retake as many times as you want but the sender will know its not your original stealthie!
Nominate your friends to join Stealthie by sending them a photo from the app. Once they sign in, they can open your photo and send their stealthie back.