straight face

Can Brown stand up with a straight face and say it's true?

He put his head on one side, but kept a straight face.

And she would have been able to say it a with a straight face.

Can you say that's a new thing with a straight face?

Can she say they are good with a straight face?

It was all I could do to keep a straight face.

Sometimes it's more about trying to keep a straight face.

It was difficult for him to keep a straight face.

She did her best to keep a straight face but it was no good.

I don't think you could keep a straight face about something like this.