I've run into this a couple times and was always curious. In what instances might you call someone by both their surname and given name? Ex. In a conversation, person B, refers to person A (named Yamada Tarou) as Yamada Tarou when speaking to them. Is this informal, formal, or rude?
1 Answer
This typically happens when you have two or more people with the same surname in your organization and they cannot be distinguished even with the suffixes such as -さん, -先輩, -課長 and -先生. If there are two 山田課長 in your office, it's fine to include their given name (e.g., 山田太郎課長) as a last resort. (In casual workplaces we also hear 太郎課長, too.)
Much less commonly, a full name is occasionally used to imply a psychological distance. If someone suddenly started to say 山田太郎課長 even though there is no need to disambiguate, I probably feel they are upset about him. (I think English speakers do similar things to scold their children. It's in the same vein.)