(YOU) COULD HAVE FOOLED ME.

(You) could have fooled me.: translation

Inf. I would have thought otherwise.; I would have thought the opposite. •

Henry: Did you know that this land is among the most productive in the entire state? Jane: You could have fooled me. It looks quite barren.

•

John: I really do like Mary. Andy: Could have fooled me. You treat her rather badly sometimes.