He wasn't exactly expecting to be cornered in the kitchen, so it takes him a moment to realise he's being asked, and another moment to try and work out a coherent answer. It's pretty impolite not to answer, after all, even if he's not sure where the question is coming from or why they've picked him of all people.

"Earth. One of them, anyway, there's a lot of people here from different Earths. Or did you mean New York?"

He keeps his tone friendly, but he can't help sounding a little puzzled as well.