"What are you babbling about Sarah?" said Sarah's old body to Roy. "I don't have boobs. And you certainly do. I mean... just look down at yourself. You sure look like a woman to me. And if you're really a guy and I'm a girl, then why did you sleep with my roommate Jack last night? I'm sure he would've noticed if you had a penis! I've known Jack since high school, Sarah. He's not into that gay stuff at all."
"B-B-But... I'm not a girl!" Roy stammered. "Just look at me!"
"Go look at yourself, Sarah," replied Sarah's old body, now firmly believing she was actually Roy. "Actually go look in a mirror."
Roy stepped out of the small kitchen and walked over to a cheap, decorative mirror hanging up in the living room.
"Ohmigod!" he cried out in surprise.
The reflection staring back at him in the mirror was that of Sarah Howard -- his roommate's girlfriend.
"Y-Y-You've got to believe me," Roy stuttered. "This isn't what I see when I look at myself. I mean... in the mirror, I'm Sarah... and I've got her face and her hair and... crap, I've got her tits! But... this isn't what I see when I look down at myself!"
Sarah's body frowned at Roy silently for a moment before speaking.
"I believe you, Sarah," she said finally.
"I'm not Sarah!" protested Roy.
"Shut up and listen for a minute," said Sarah's body. "You know all about the little gizmo my clone from another world gave to me. You couldn't have known about that otherwise. I just got the device and haven't even had the chance to test it out yet, much less tell anyone about it. And more importantly, you're not acting ANYTHING like the real Sarah. There's no way the real Sarah Howard would get all hysterical like this and make wild, crazy claims that she was actually... a man! The truth is stranger than fiction, they say. Your story is just crazy enough to be true. I believe that you used to be... well, me. Or maybe another version of me or something. Look: I believe that YOU believe you're really me. But, as far as the rest of the world is concerned, you are Sarah Howard. What you see in the mirror there is exactly what I see when I look at you. And I certainly don't see boobs or anything womanly about my body. When I look down at myself, I see good old Roy -- 100% normal. So... I wouldn't expect anyone else to believe your story. I get the predicament you're in... and I really do believe you. But nobody else is going to."
Roy collapsed, stunned, into a nearby armchair.
"So... I have to be you?" he said.
"No," replied Sarah's body. "I'm Roy. You have to be Sarah. That's who everyone else sees when they look at you."