"You never know when you might need it," said Martha, with dry humour and more than a little honesty. "And no, actually..." She felt her cheeks heat a little, and took a sip of her drink (more like a gulp). "This one just looks like a skinny tall bloke with messy hair, like a human. Except he has two hearts. I mean, we met aliens that didn't look human at all, but not the Doctor. He'd blend in if he didn't make himself stand out so much," she said, fondly, if with a bit of remaining exasperation.