The closest answer I can think of is "才怪".
A: "In a few years I'll be driving a Ferrari."
B: "As if you'll ever have a Ferrari!"
怪 means incredible in English 惊异，感到奇怪
才 means having the ability (能力：～能。口～。这人很有～干)
才怪 is evolved from the longer phrase "才奇怪" and the usage of which only becomes popular in recent times. If you are interested, you can read up this article which describes at length the historical development of the phrase.
Quoting from the article,
Translated to English:
才怪 slowly evolves to mean an expression of disagreement. The words "disagreement" and "incredible" are closely related. To think that something is incredible implies that the person does not agree that it will happen. Only when a person disagree with something would he find it strange or out of the norm. Therefore, we believe that the contemporary meaning of
才怪 is an expression of disagreement and evolves from the longer phrase
In my own words,
才怪 has the same exact meaning as "as if it would happen".
A: I'm not going to smoke again, I promise.
B: As if this is going to be your last cigarette.