How to guess other people's surnames

Is guessing other people's surnames a common trick on the street? The first time I saw this, I thought it was a fool. It's too easy to earn three yuan at a time. This game is actually the same as guessing numbers. Fingering is a cover. He guessed his last name from the card instead of pinching his fingers out of thin air. Simply put, fortune telling is to put a rectangular plastic plate on the ground with 5*3 large squares, each with 30 whole surnames, totaling 450 surnames. In addition, he holds a stack of cards with many surnames on them. From these cards, you find the card with your surname written on it, and then find the big box with your surname written on the cloth on the ground, and buckle the card upside down in the corresponding big box. The secret is that each card has a number mark, and the fortune teller can know the surname of the person being counted as long as he remembers which surname each card overlaps in different positions. These are all trained people.