you could have fooled me

(you) could have fooled me

Really? I thought the opposite was true. A: "This neighborhood has really improved in recent years—it's quite popular now." B: "Wow. With all the boarded-up buildings, you could have fooled me." Maria is shy? Could have fooled me. She was talking all night.
See also: could, fool, have
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

you could have fooled me

People say you could have fooled me to show that it does not seem to you that something is true. `I came here to apologize.' — `You could have fooled me.' Car makers are supposed to be bringing their prices down. Well, you could have fooled me.
See also: could, fool, have
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012
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