Answer: Your cup!
In an effort to get more customers to bring their own reusable cups, Costa Coffee in the UK has announced the launch of an NFC-equipped reusable cup. The Clever Cup has a removable bottom layer that contains one of Barclay’s NFC chips for contactless payment.
Users add money, up to £15 (about $19.25), to their cup through the bPay app. bPay is Barclay’s larger contactless payment initiative, which includes a variety of wearables and other devices that include its payment technology. The Clever Cup will work anywhere that NFC payments are accepted, so theoretically you could use it to buy coffee at non-Costa locations that also use the tech (although you do so at your own risk).