At first, Facebook’s new ephemeral messaging app, Slingshot, feels like yet another Snapchat clone. But in Slingshot, you can’t view an incoming shot until you send a shot back to the sender. It’s not just about telling your story, it’s about asking others for their story, says Slingshot designer Joey Flynn. In other words, Slingshot makes you trade a photo of what you’re doing before you can unlock the picture of whatever your friend is up to.