you must be kidding (me)

you must be kidding (me)

You cannot be serious; I don't believe it; this can't be true. A: "Did you hear that Sam got promoted to General Manager?" B: "You must be kidding me! That guy couldn't manage his way out of a paper bag!" Oh, you must be kidding! How can the traffic already be so backed up?
See also: kid, must
Farlex Dictionary of Idioms.
See also:
  • you have got to be kidding (me)
  • You've got to be kidding!
  • you're kidding
  • you're kidding (me)
  • (Are) you kidding (me)?
  • who am I kidding
  • me
  • aside
  • no kidding
  • No kidding!