All you have to do is sign for him. The relationship between you is only "entrusted" and there is no guarantee. The credit card can only be used after it is activated by itself. All expenses after use will be borne by the credit card holder and will not affect you.

Credit card, also called debit card, is a credit certificate issued by a commercial bank or credit card company to eligible consumers. It is a card with name, expiration date, number and cardholder's name printed on the front, and a magnetic stripe and signature strip on the back. Consumers with credit cards can go to specialized commercial service departments for shopping or spending, and then the bank will settle accounts with merchants and cardholders, and cardholders can overdraw within the prescribed limits.