The Doctor's eyes fluttered closed momentarily at the feel of Jack's mouth on his jaw, and one hand flew up to the back of Jack's head, not to hold him there, just to... encourage.
"I haven't done anything in this body," he admitted, when he could speak. "It's brand new, just a day or so old." He looked down his nose to meet Jack's bright gaze with a playful one of his own. "What would you like to do with it?"