/Neih/ gwai sing a?
What is your (honorable) surname?
/Neih/ giu -mat-/yeh /mehng/ a?
What is your name?
(What are you called?)
/Ngoh/ sing ~
/Ngoh/ /siu/ sing ~
/Ngoh/ giu ~
My name is ~
Formality and respect
In Cantonese it is polite and customary to first ask a person's surname. While the translation to English may appear overly formal, Chinese culture demands the honorific "gwai".
In Cantonese, "/Neih/ gwai sing a?" can be shortened to "Gwai sing?"
The Reply #2 in the pattern above, "/Ngoh/ /siu/ sing ____" is both polite and formal. The humble "/siu/" has the exact opposite meaning as "gwai". While using this answer may make a good impression in some situations, it is generally too formal and is not used much in modern society.