According to Japanese site Rocket News, the new iPhones can recognize your nipples (um, okay!), keeping it locked for different nipples.
In the above video, you can see an iPhone owner register his nipple and lock his new iPhone. Then, a different man unsuccessfully tries to unlock the phone with his nipple. Guess this proves our nipples are all different. That's good to know!
It's not only nipples that apparently can be used, but also toes. So, if you think using your finger to lock your new iPhone is tres passe or if you are simply worried, bust out a nipple or a toe to secure your iPhone. One day, maybe you can bust out both.