in your dreams

dream on

A slang retort indicating one's skepticism. Oh, dream on—you'll never become a famous singer. A: "I really think I'm going to get the promotion." B: "Dream on! I have a much better chance of getting it than you."
See also: dream, on

in (one's) dreams

A derisive phrase said in response to something that is far-fetched or unlikely to happen. You think you can get a date with the head cheerleader? Yeah, in your dreams! Matt is only getting a promotion in his dreams. I'm much more qualified for the job than he is.
See also: dream
Farlex Dictionary of Idioms.

Dream on.

What you are expecting or wanting to happen is nothing but fantasy. You want to get promoted to general manager? Dream on. You, an opera singer? Dream on.
See also: dream, on
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

in your dreams!

COMMON People say In your dreams! to say that what someone wants is never going to happen or be true. Stephanie in love with you? In your dreams! He seems to think he is the next great comedian. In your dreams, lad.
Collins COBUILD Idioms Dictionary, 3rd ed.

in your dreams

used to assert that something much desired is not likely ever to happen.
2002 New Yorker Before falling asleep, I try to imagine myself as…a savvy entrepreneur with her own catering business. In your dreams, as they say.
See also: dream
Farlex Partner Idioms Dictionary

dream ˈon

(spoken, informal) used to tell somebody that an idea is not practical or likely to happen: ‘Do you think if I ask my boss for a pay rise, I’ll get one?’ ‘Dream on!’
See also: dream, on

in your ˈdreams

(spoken) used to tell somebody that something they are hoping for is not likely to happen: ‘I’ll be a manager before I’m 30.’ ‘In your dreams.’
See also: dream
Farlex Partner Idioms Dictionary

dream on

v. Slang
To fantasize about something that is improbable or unrealistic. Used chiefly as a scornful command: So you want to move to Hollywood and become a movie star? Dream on!
See also: dream, on
The American Heritage® Dictionary of Phrasal Verbs.

in your dreams

Never, no matter how much you wish for it. Often put as an interjection, this slangy term dates only from the 1980s but has quickly caught on. For example, “I just know they’ll win the pennant this year.—In your dreams!” A synonymous phrase is dream on, used as the title of a number of popular songs dating back as far as the 1950s and a television sit-com.
See also: dream
The Dictionary of Clichés by Christine Ammer
See also:
  • dream on
  • a pipe dream
  • pipe dream
  • dream house
  • dream
  • dream up
  • live in the past
  • nourish
  • delay
  • desires are nourished by delays