Bang With Friends is an iPhone app that will anonymously match up people who are already Facebook friends for casual sexual encounters. Created by three anonymous Californian college students, the app only notifies both people when there is a match in the system. Within a week, the app's user base has exceeded 30,000 with its creators claiming that five people are signing up per minute. But don't delete your Grindr account! There's no option for same-sex hookups at the moment, but it is apparently in the works. Hat tip to Mashable.