"Is it really that interesting?"

Martha jumped guiltily and looked round to see her watching herself from the doorway. Or rather, the Doctor. Blimey, this was confusing.

She tucked his shirt back into his trousers and blushed. "Sorry. I was just... umm..."

"Honestly," he sighed, "you humans. Two hearts, respiratory bypass, fantastic cerebral cortex, three extra senses, lightening reflexes and what do you do with it? Stare at my cock."

"I didn't mean to!"

"What about your medical detachment? I'm sure you must have seen one before. Isn't that why you lot invented the internet?"

"Fine," she said, "I'll admit it. I wanted to see if it looked alien."

The Doctor raised an eyebrow, which surprised Martha because she didn't think her eyebrows could do that. "So it's okay if I have a look in your knickers to check if your reproductive organs look human?" He reached for the zip of her jeans.

"Don't you dare!"

"Can I look at your breasts?"

"Do you have to?"

The Doctor glanced downwards. "It's quite hard not to. They're very... there."

"Same with your... you know."

"Is that a medical term?"

"Penis. There, I said it. Penis penis penis."

"And does it look alien?"

"No," said Martha, not bothering to hide her disappointment.

Either it was the new senses or this body had a really good imagination to go with it, but she'd swear she could see his ego flinch.

"Well," he said, defensive, "there's only so many things it could look like. I think it's nice. It gets the job done."

"I didn't say it wasn't nice, I just said it didn't look alien."

"So at least next time we're about to die you won't get distracted wondering what's in my trousers."

"I never do that!" she lied. "Anyway, I thought you liked my curisoity."

He leaned against the doorframe with a sigh. "I don't mind. Really. I don't have -" He paused. "Hmm. Must be cultural rather than biological. Funny how having someone else's brain can make things suddenly obvious."

"You don't have..?"

"Hang-ups. Not about that." He gave her an offended look. "I'm a Time Lord, Martha, I've got a unique understanding of the underlying fabric of the universe itself. Time and space and injustice and burnt toast. You think I'd waste effort worrying about whether you've seen my cock?" He squinted at her. "Blimey, I've got a nice arse."

"It's all bones and skin," said Martha, spitefully. "Your whole body is. It's like being broom handle that someone's wrapped in a white plastic bag. And it's too cold."

"Lower body temperature. Do you see me complaining about this sauna you call a body?"

"And your hearts, how do you sleep with all that racket?"

"At least I don't expel my womb lining every lunar cycle."

Martha looked down at her... his stomach. "You've got a womb?" She poked at his/her abdomen.

"Course I haven't!"

"You're an alien! How do I know you don't have a womb? Wait a minute, aren't you supposed to be fixing this?"

He stared at his feet. Or at least tried to, but Martha's breasts were indeed very much there. "I got a bit..."

"A bit?"

"I can't hear her," he said, as though it were obvious.

"Who?"

"Her." He touched the wall carefully.

"Oh."

"So it's a bit difficult. You know. Poking around inside a woman without knowing whether she likes it."

"You've got a filthy mind."

"Excuse me, Martha Jones, it's your filthy mind. You're the one with the hormonal overload."

She shrugged. "You're ovulating."

"I know. I keep thinking about sex and babies and knitting."

"Knitting?"

"That's what I've been thinking about to avoid getting distracted by all the sex. I've mentally knitted three jumpers and a balaclava."

"Oh, and your body doesn't go in for that sort of thing."

"No, it doesn't."

"This begs to differ," she said, pointing downwards.

The Doctor stared. Finally he said, "Right, I'm going to go get us back in our own bodies before we end up having sex."

"You do that."

"Just don't... touch anything."

"What about poking the TARDIS?"

"If you get a sudden splitting headache then I've connected the wrong wires."

"Right," she said. "Thanks. Oh, and Doctor?"

"Yeah?"

"Nice tits."