Comprehensive resource for understanding and mastering English idioms
The idiom "so and so" is used to refer to a person or thing without using their name directly. It is typically used as a placeholder until the specific name is known or in cases where it is deemed inappropriate or disrespectful to use their name. For example, if someone asks you about a colleague or classmate and you don't know their name, you might say something like "Oh, I believe you mean so-and-so."
The origin of the idiom "so and so" is unclear, but it has been in use since at least the 16th century. It may have originally been used to refer to someone whose name was unknown or who was being referred to indirectly for reasons of politeness or discretion. Over time, the usage of the idiom has expanded to include situations where using the person's name directly is inappropriate or disrespectful.