poker face
US /ˈpoʊkər feɪs/
UK /ˈpoʊkər feɪs/

1.
visage impassible, visage de poker
an impassive expression that hides one's true feelings or intentions
:
•
Despite the bad news, she maintained a perfect poker face.
Malgré les mauvaises nouvelles, elle a gardé un parfait visage impassible.
•
He tried to keep a poker face during the negotiation, but I could see his excitement.
Il a essayé de garder un visage impassible pendant la négociation, mais je pouvais voir son excitation.