0 a serious expression on your face that you use when you do not want someone to know that you think something is funny: --
Blake looked ridiculous in leather trousers, and I was desperately trying to keep a straight face.
1 an expression on your face that shows on emotion in order to hide what you really think or feel: --
With an entirely straight face he gave attractive examples of the regulations which are likely to be reduced or repealed.
I shall do my best to keep a straight face and take them seriously.
With an almost straight face, he tried several times to pretend that there was no filibuster yesterday evening.
Can he look across at me with a straight face and say that he believes that people's civil liberties are being damaged?
One can only applaud the commitment to national self-interest that can produce such a tenuous argument with a straight face.
We all realise that it is extremely difficult to deliver that answer with a straight face.
He was able to make his remarks with a perfectly straight face.
I simply do not know how he managed to keep a straight face as he read out those comments.