call someone's bluff
US /kɔl ˈsʌm.wʌnz blʌf/
UK /kɔl ˈsʌm.wʌnz blʌf/

1.
desafiar el farol de alguien, poner a prueba a alguien
to challenge someone to prove that what they are saying is true, or to show that they are not afraid to do something that they have threatened to do
:
•
She threatened to quit, but I decided to call her bluff and see if she would actually do it.
Ella amenazó con renunciar, pero decidí desafiar su farol y ver si realmente lo haría.
•
The politician made a bold claim, and the journalists decided to call his bluff by demanding evidence.
El político hizo una afirmación audaz, y los periodistas decidieron desafiar su farol exigiendo pruebas.