Don't use a rubber ring the way they dock a lamb's tail.
See a doctor who specializes in this kind of thing. I have heard that men wanting to either reassign their gender or simply to dress as women can take estrogen and that it minimizes the male genitals after a while, but have never heard how much. The only man I ever talked to who was into dressing female, looked great (in other words, you would not be able to tell he was anything but a very striking woman) even in a swimsuit, and although he was doubtless taking hormones, he had not had an operation.
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