One of the easiest ways to pay in BitCoinBTC in person is with a mobile wallet app from a smartphone. Blockchain a mobile wallet app for Android and iOS. It's an online wallet, so I wouldn't recommend it for long-time storage: strictly transactions. Once I know how much I need to pay for an item I put that much in the wallet, and maybe 1 or 2 BTC more just in case there's a last second price change, and when I get home I immediately transfer any leftover funds to a more secure wallet. Blockchain works the same as any other client: enter the seller's payment address and the amount of BTC for the sale to send payment. Blockchain also has a QR scanner built in if the seller has a QR code address.