Definition & Meaning of "[go] on (and on|) about {sb/sth}"

What is the origin of the idiom "go on about someone or something" and when to use it?

The origin of the idiom "go on about someone or something" is unclear but it likely comes from the phrase "to go on" which has been used for centuries to mean "to continue" or "keep speaking". This idiom was popularized in the mid-1900s and captured in songs, books and movies to describe someone who won't stop talking. It is typically used in an informal or conversational context to describe an emotionally negative experience of listening to excessive details about a topic that the speaker finds boring or uninteresting.