I wish!

I wish

An exclamation that shows the speaker's belief that something will not happen in the ideal way another person proposes. A: "Do you think you'll get an A in this class?" B: "I wish! I would need to ace my final project and my exam just to have a chance of bringing my average up."
See also: wish
Farlex Dictionary of Idioms.

I ˈwish!

(spoken) used to say that something is impossible or very unlikely, although you wish it were possible; if only: ‘You’ll have finished by tomorrow.’ ‘I wish!’
Farlex Partner Idioms Dictionary
See also:
  • hoo-rah
  • viola
  • voilà
  • ah
  • gotcha
  • be still my beating heart
  • be still my heart
  • boom goes the dynamite
  • dynamite
  • snap