Call someone’s bluff Informal

To challenge a person to prove that they mean what they claim or threaten, especially when you suspect they are pretending or will not follow through.

Bluff became prominent in English through card-playing, especially poker, where a player can bet aggressively while holding a weak hand to persuade others to fold. To call a bet means to match it and force the hand to be tested. From that gambling context, call someone’s bluff developed into a broader expression for refusing to be intimidated by a threat or bold claim and demanding proof. The idiom is not simply about insulting someone or daring them for fun: the essential element is exposing a possible pretense. Today it applies to negotiations, workplace disputes and everyday promises. Although the metaphor is clear, individual claims about the first person to coin the phrase should be treated cautiously.

He threatened to resign, so the manager called his bluff.

She said she could run a marathon tomorrow, and I called her bluff.

The landlord demanded more money, but we called his bluff and refused.