Make something out of the thin air

無中生有

空氣是無色、無臭、無味,有它怎可能做出什麼呢?因此,可以說,從空氣做出一些東西來,便是無中生有了。

eg.     A: If I were you, I would not believe what Johnny said.

        B: What makes you say so?

        A: He is notorious for making something out of thin air.

        B: Are you telling the truth?