“Ow,” said Rose, and stuck the tip of her finger in her mouth and sucked.
The Doctor stared.
“Paper cut,” she said.
Paper cut, thought the Doctor, in awe, and spent the next few days handing Rose various bits of paper, in the hope that she would get another paper cut.
When it happened, finally, he almost missed his chance.
“Ow,” said Rose, and lifted the afflicted finger up—
--And he intercepted it, grabbing her hand and sticking her finger in his mouth and sucking on it.
“Better?” he asked, eventually.
“You lunatic,” she said, and snogged him senseless.