Last Name, First Name Antics

Deng Deng is a tutoring student of mine with the same first and last name. While helping him to fill out a form, I inadvertently gave him some ridiculous advice. "Deng, when filling out your name in this box, don't forget to write your last name first." After a few seconds, we both looked at each other and started laughing. He said. "That's never a problem for me."