What do you call someone who responds to everything you say?

My cousin always tend to say something in response to everything I say, what do we call people like that? I'm just curious to know because I want to call him something. xP

Lisa B2012-03-29T12:44:42Z

Favorite Answer

Well, if it's more annoying than nice, you could call him a compulsive responder.

djrob19432012-03-29T19:37:35Z

Nice?

kaliesq2012-03-29T19:30:33Z

engaged (in the conversation, with what is happening) and polite
Be nice

A. Ang.2012-03-29T19:32:26Z

an answerer?