"Now, for your transformation, whenever you get turned on, you will change into whatever I find sexy at the moment. Your clothes will also change with you if you are wearing anything. But just to make sure that it won't affect things too much for you, after an hour you have transformed into whatever is sexy at the time, and you will turn back to your normal self."
Your girlfriend is starting to understand why this game is cursed. While she may have her times of feeling "extra", the fact that she could transform into something that she may not be happy with is not what she wants. And that was just the Transformation. If the Transformation could be as bad as turning into a sexual freak any time that she is "in the mood", how bad is the Dare? She just hopes you don't her into something freaky.
"As for your Dare, when you become your "Sexy Self", you will develop an identity based on your looks. Think of it as method acting, but only in bed. As for another nice thing to do, you would remember being your "Sexy Self", so that you wouldn't miss out on things if you were away. And to start this new way of having sex, when I am finished speaking, you will instantly be turned on."
Before your girlfriend has a chance to say how wrong it was to control her this way, intense arousal spontaneously erupts within her. It was a feeling that she had only once had when she first had sex with you. But unlike that first time, there was another feeling as well. It was a feeling that her flesh and bone were changing and moving about. By the time that your girlfriend has calmed down from her arousal, she has turned into what you were thinking of that is sexy.