There are some submissive males out there that actually fantasize about having their dominant partner or a mistress surgically castrating them. In their fantasies these men then become their mistress s slave and they worship her. In reality, there really are some women who do perform this and an internet search will get you more details.
There are also some women who have these femdom castration fantasies too. In these fantasies it is the woman that actually castrates the man. What these women feel or what their fantasies involve has yet to be discovered but it is true that if you truly wish to be castrated at the hands of a dominant female it is possible although for many men a mock castration is enough to fulfill their fantasies. This involved role play in which the woman pretends to castrate the man and this can be in the form of cock and ball torture methods.