A style of comedic delivery in which something humorous is said or done while not exhibiting a change in emotion or facial expression.
In a deadpan manner.
Impassive.
Deliberately impassive or expressionless.
Having such a face or look.
To express (oneself) in an impassive or expressionless manner.
Any similar expression used to prevent giving away one's motives, feelings, or situation.
An impassive facial expression cultivated to prevent other players from determining whether one's actions in the game are the result of a quality hand, or of bluffing.