What is a muff?

Answer 1

It is slang for the female external reproduction organ the vulva

Addition: To people my age -- old -- the slang term is not unknown, but the word "muff," out of context, is more likely to evoke an image of an article of clothing worn by women; specifically, a hand-warmer used in place of gloves.

Both women and men sometimes wear articles of clothing that serve to protect their ears in cold weather--so-called "ear muffs."

There are also "ear-defenders," headsets that serve to protect the ears against loud sounds. Such devices, also known as "muffs," are used in industry and in the military.