I know what you're thinking: "Oh, no... not another social image sharing app!" And if this were anything like that, I'd share you sentiments. But it's not – it's actually quite refreshing, because this app focuses solely on sharing and not at all on social.
Here's the gist: you take a pic – called a Rando in this case – and send it anonymously to someone in a completely random place elsewhere in the world. In return, you also get a Rando. And you must send one to get one. All transfers are completely anonymous – you won't know who got your Rando, and likewise won't know who sent the one you got.