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
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