I have to agree and disagree with Hao Peng... the sentence, despite being grammatically correct, does not completely retain ALL the Chinese meaning. 还不， in this sentence shows that it's not the first time this has happened. there's a feeling of "你怎么还不跟我聊天呢?“ Why don't you chat with me now? There's a feeling of resentment missing. It does not retain this feeling at all. "Since you have nothing to do" is accurate enough for the first translation, but I personally change the whole thing to: You have nothing to do and you are still not talking with me? <<还不 are still not

i guess "why not ... now" is the best answer. anyway, "why not" could be translated as "为什么不". since you have nothing to do, why don't you chat with me now?

agree with Hao Peng,

since u have nothing to do , how abt chatting with me for a while ? 还不 express ur suggestion for chatting . i think maybe ''how abt , what do u think of .... '' works ^ _ ^