It is a fact that the average size of a male penis is around 5 1/2 inches. Just as there are men that have an above average size penis there are women that have an extremely large vagina. It is probably a certainty that a woman that engages in "fisting" probably wouldn't be satisfied by any man's penis no matter the size, if size is that important. It has been my experience that it is not the size of the tool but the technique. Most women have an orgasm when the penis comes into contact with the clitoris. After a certain depth the vagina does not have any nerve endings.