[Oh hey there, Donatello, you're actually the first noticeably non-human person Kay's met. If her eyes widen a moment, if her eyebrows raise, it's because she's never met a talking...turtle? before.]

[In a low voice--] You weren't kidding. [And then, with a genuine smile, if perhaps a slightly belated one--] Nice to meet you, Donatello. I don't think I've come across anyone else from the city yet.