Talk a blue streak意思

"Talk a blue streak" is an American English idiom that means to talk very rapidly and in great detail about something. It implies that the person is speaking so quickly and with such enthusiasm that it's like a constant stream of words, almost as if they were talking non-stop. The phrase is often used to describe someone who is very talkative and who has a lot to say on a particular subject. It's not a common expression in British English.