Can I swipe someone else's credit card when shopping in duty-free shops in Japan?
At least don't borrow cards to make gender differences (laughs). If the situation with the credit card holder is too bad, many responsible clerks will still ask about your relationship with the cardholder, and no matter who swipes the card, a customer will sign or enter the password in the end. I live in Japan, and I believe it should be the same in China.