Satan's Handmaiden

While having breakfast in a coffee shop, Peter Crawford, an aging and impoverished man, is approached by a young woman who tells him that she's a demon--actually Satan's Handmainden.
Peter, of course, doubts her assertion and asks her for proof of her unlandish claim, to which she suddests that they go to his apartment where she'll give him a living proof of her assertion, but in private. To which her agrees despite the strangeness of the entire affair.
The woman, who calls herself Debra, does exactly as she had offered and they have a glorious session of sexual pleasures throughout the afternoon. Then, when she is accepted by Peter as whom she is supposed to be, she offers him a final proof and suggests that he'd probably appreciate it if they exchanged bodies for a short while so that he'll be able to understand what being a woman means. Peter, as most men do, had always wondered what it would be on the flip side of his gender, and readily agrees to Debra's proposal.
To his great delight, the experience is quite thrilling. Then, when he asks for his own body back, Debra tells him with a chuckle that she had duped him in order to acquire a male body, and that he's forever stuck in her body.
When he claims that she had been dishonest with him, Debra's reply is "Of course I did. I'm a demon after all."