Why do you talk nonsense all the time?

你怎么老在胡言乱语啊？

If you're going to talk nonsense, I won't listen.

你要是胡说八道，我就不听。

Sir, you've been talking nonsense and make me talk nonsense. It's hardly fair.

先生，你在胡说，也害得我胡说。这不公平。

You must not talk nonsense.

不许你胡言乱语。

How do you know? Don't talk nonsense!

你怎么知道的，别瞎说！