Knock Knock?

Knock Knock? Who’s There? No, it’s not the beginning of a joke, it’s the basis of the new contact app “aimed at the college-age crowd” that wants to make connections and information swapping simple. Users simple make a “knock knock” gesture on their phone screen—whether or not the app is active—to share contact info with “who’s there,” the other users in the vicinity. (The Next Web)