Definition
Used to express the speaker's skepticism about another's preceding statement about a desired or assumed state of affairs.
Also Said As
- dream on
- you wish
- in your wildest dreams
How People Actually Use It
(idiomatic expression) To express denial, to refuse a proposal. Same as "I don't even think about it" or "Fuck you, I won't do it!".
""Drop your weapon!" "In your dreams..." (during a robbery)"
Source: Urban Dictionary