It's hard to single out the worst part of Titstare, a "joke" app presented Sunday at TechCrunch's Disrupt 2013 startup conference hackathon. Everything about it — the name, the concept, the presentation, the context — is just jaw-droppingly "no." And yet, it just happened on a stage, before an audience that, from the video, sounded at least somewhat receptive to it. Titstare, from Australians Jethro Batts and David Boulton, was the first presentation of the day. As Boulton explains in the presentation, their product, which was meant as a joke, "is an app where you take photos of yourself, staring...