"NO!" you say in your new voice, "Why? Why do this to me?"
The woman responds by giving you a piercing gaze that penetrates deep into your soul. Her eyes have a tone of coldness and mercilessness of an animal that had killed its would-be predator.
"You came here, Wandering Tom," she said, "into my home and into my shower. You wanted to be here and wanted to be in a woman's shower? I simply gave you your wish. You're now a girl."
Your mouth opens and closes in protest, as you try to ignore the pleasant sensations the water is giving your body. It feels so fresh and free and beautiful, but you try hard not to focus on it.
"It took me a long time to master that spell, you know. Normally my kind need a little more direct a method."
She gestured with her hands which you could swear had a small eerie glow to them, but left quickly.
"Suffice to say," she continued, "I don't like men. I never have, and I don't think I ever will. Those men who cross me get to learn from their mistakes for the rest of their blessedly beautiful lives. And now you have two choices."
She smiled and snapped her fingers. You suddenly find yourself in a different room: dry and in a pretty gown that hugs your curves and makes you squirm a bit. You are in a chair at a table across from which she is pouring tea. A girly tea party in a mansion dining hall. Eep.
"One is you can go home and make the most of your new life," she said, "the other is to stay here with me... and learn my secrets, as your attitude has been admirable in comparison to the former roughnecks who would be screaming their heads off at me by now."
The choices are there now. Will you stay with her and try to sort our your new life? Possibly find out what she meant when she said 'her kind'. Is she not human? Maybe she'll teach you magic and you can be a man again!
However...! That choice loses some luster in the fact that she doesn't look like she ever turns people back or wants to lead them to having their lives back. Living with her might be a sentence to a lifetime of femininity -- judging by this gown that now clings to your new body.