While Touch ID is designed to scan the fingerprints of your fingers (and thumbprints of your thumbs), some users of the iPhone 5s have discovered some other body parts that are supported by Touch ID. For instance, the video above shows a user registering their nipple for Touch ID. More videos and body parts below:
Another iPhone 5s user shows the functionality working with a toe in the video above.
Our friend @chronic notes that Touch ID can even work with a user’s nose, and a video that we found on YouTube (shown above) demonstrates this.