Did your parents make any jokes when they first paid by mobile?

Not long ago, my parents were shopping, and I met a begging old man on the road. He looks so pathetic. He was going to donate some money to the bowl in front of him, but he rummaged through his pockets and found that he didn't bring any cash. At this time, the old man quickly took out a QR code from the side. But they don't know how to pay, so let grandpa teach them. . .