Definition & Meaning of "muff diver"in English

What is the origin of the term "muff diver" and how is it used?

Muff diver is a slang term that appeared in mid-20th-century English to describe a person, often a lesbian, performing oral sex on a woman. The word "muff" is a crude slang term for female genitalia, and "diver" emphasizes the act of oral penetration. Historically, it was vulgar and sexualized, used to describe sexual activity in a blunt or mocking way. Today it remains offensive and explicit, and using it outside sexual or historical discussion is likely to shock or insult.