Apparently a couple has exchanged RFID tags in the US. The radio beacons, implanted under their skin, give them access to each other's house, car, computer and so on.
This sounds very modern - they're also modern enough, you'll notice, to be a couple but not to actually be living together - and it certainly could have practical benefits.
Take me, for instance. I'm currently not exactly sure where my wedding ring is. I took it off because it was irritating a cut on my finger, and Alison put it in a drawer to keep it safe. But which drawer?
Now, if we'd had RFID tags implanted instead, there'd be no danger of losing them.