What does “government name” mean in English slang?

Introducing this cat’s brother, the owner jokes, “Lieutenant Dan, that’s his government name.” Your government name is your full, official name, the one on legal documents, not your nickname. Saying it about a pet is a joke: it treats “Lieutenant Dan” like a formal legal name, as if the cat had ID.

The phrase comes from informal, hip-hop-influenced American slang, where it separates a person’s real, legal name from a nickname or stage name. People now use it jokingly in many situations: “Don’t use my government name in front of my friends” means “don’t say my full, formal name here.” It always adds a little humor or seriousness to naming someone properly.