As a woman it is one of the hottest things ever, especially “straight” men, then their masculinity disappears and they realise what they truly are.
Just watching their face, they are excited, scared, worried, all emotions, a cock presses up against their ass and they get more worry on their face and more and more pressure until finally it slips in and wow the face of relief. And lust and craving more and more. Once you take a cock there is no going back.