call somebody's bluff
call (one's) bluff
1. To challenge someone to act on their threat or prove that their claim or boast is true, when one believes they are making a false claim or idle threat (i.e. bluffing). He insisted that he could run faster than me, but when I called his bluff, he suddenly said he had to go home.
2. To disprove a bluff. Whereas the first usage simply indicates a challenge, this usage indicates that the challenge resulted in the disproval. I don't know why he keeps making these outrageous claims. I've been calling his bluff for years and making him look like a fool.
call somebody’s ˈbluffgive somebody the chance to do what they are threatening to do, because you believe they will not or cannot do it: Next time she offers her resignation, they’ll call her bluff and accept it.
If you call somebody’s bluff in the game of poker, you force them to show their cards.