12 falls into something nasty on an alien planet. Clara helps get him clean (with lots of lovely hair washing and combing preferably) and both of them find this surprisingly arousing and they do the do.
Not quite as far as the doing the do part, but I got the goo and shower parts of the prompt!
“We’ve got to get this mud off! Now! Run!”
The Doctor clutched Clara’s mud-smeared hand and tugged her into motion. She ran slower than he did, mere human that she was. Short-legged short human. He had long-since learned how to pace himself to match her, not that he admitted this. They ran, hand in hand toward the TARDIS.
Clara was protesting.
“It’s just mud,” she said. “Green mud, yeah, but the dirt was green because of all the copper so–”
“It’s not just mud, Clara. It’s semi-sentient nano-mud. It’ll be reconstructing our bodies along more efficient principles if we leave it to dry.”
It was, he did not add, already likely cleaning up her outermost skin layers, removing pesky moles and doing things she might or might not like with hair follicles. If it took a mind to it. It was unpredictable. That was the trouble with semi-sentient things. You could reason with things that were all the way sentient. You could talk to them, find how how they thought. Sometimes they were annoying, but mostly they were fun. This was why he did what he did for the universe. Why Clara ran around with him helping him. But semi-sentient things were flighty. Nervy. Whimsical. In a word, unpredictable. He hated things he couldn’t talk to.
Right. Back on topic. Mud.
“We need to get it off ourselves. Now. TARDIS bathhouse. Chop chop!”