I'm not sure if this has ever been implemented yet, but can you imagine a way of paying with Bitcoin by just using your own body?
It would be more of like a microchip implanted into your left or right hand that would contain both your public and private keys to send and receive Bitcoins.
So in case you want to send or receive some BTC, you would just pass your hand over at a scanner and it would perform the desired operation. This is would make it a very convenient and easy way to transact, and carry your Bitcoins with you anytime, anywhere. However, the only thing to be considered would be the security of your private key from within your implant, to protect your funds from theft.
Nevertheless, I want to know your opinion about this, since it would be pretty cool to have such a system to help spread mass adoption of the cryptocurrency.

Looks like a very attractive idea and can really be an icon for being a very technologically-advanced person. However, there would be many who can be turned-off with the idea. I for one may not go with it as it can invade my own privacy even if it is just my thinking. Plus it can be dangerous...we can be kidnapped and be forced to do Bitcoin transactions because the chip is inside of us lol. But I think there can be a good market for this and the technology behind can have other uses too.