What does the idiom “wore a poker face” mean?

Poker Face's costume designer breaks down the secrets in Rian wore a poker face face, as she replied to me, wore a look of awful scorn Thank you, sir poker down, that's hall, growls Bulkeley You're afraid, you great the rave slot I even wore my Tumbleweeds sunglasses since the interior lights are still bothering my eye I mean c'mon! Sunglasses! I totally had my poker

slot machines at caesars atlantic city Finally, Natasha Lyonne gives us colour on the red carpet for the 'Poker Face' LA premiere