Aw, that puzzled look is completely adorable! Jack grins, can't really help it, because - hey, even if he didn't mean to and has absolutely no idea how it happened, he's managed to make the Doctor pull an entirely too cute expression.

"Dunno," he answers with a shrug. "Thought I was in Rome, actually." He gives a pretty vague motion, which isn't gonna help the Doctor's cute-and-confused routine. (Does he want to, honestly?) "Some ... crazy thing with vampires? Then I woke up here. Not that I'm complaining, but if I wake up groggy in your magnificent time ship and can't remember what exactly I did the night before, I'd kinda like to assume a good time was had by all."

Sorry, Savvy, you're gonna get subjected to one of Jack's gorgeously suggestive grins. Doctors were made for flirting with, you see.