"That depends on which planet, dear. On some of them, they're perfectly hygienic, and even if they're no, they can be sterilized," came the response. "Which reminds me, we've got to pay a visit to that spongey sort of asteroid belt. It was like a bouncy castle." He grinned at the memory of it, chuckling.

At the woman's not-really agreement, the Doctor couldn't help but laugh, however sheepish that laughter was. "It's completely true!" he protested, unable to stop laughing for the moment.