Hi Cathy -
Believe it or not this is a pretty common dream. It’s almost as if we are attracted to our friend, who happens to be of the same sex, and then the dream changes to accomodate our rational objection to the fact that our friend is the same sex as we are. So suddenly our lover grows male genitalia - as if to make the sex act more natual.
Only you know what this dream really means. But if I were you I would leave myself open to the possibility that you are attracted to your friend. It’s possible (read some of the other dreams in this section), that your friend is merely substituting for your anticipation of sex with men, or you may really be attracted to her. In any case, remember that it’s natural to be attracted to your friends. That’s why they are our friends. They have qualities that we like, admire, and find attractive!