keep a straight face - Meaning in Hindi

Meaning of keep a straight face in Hindi

How did you keep a straight face? ( आपने सीधा चेहरा कैसे रखा? )
Dean wasn't sure he could greet the woman with a straight face. ( डीन को यकीन नहीं था कि वह सीधे चेहरे से महिला का अभिवादन कर सकता है। )
She managed to say it with a straight face and rinsed the bubbling blood off under the faucet. ( वह इसे सीधे चेहरे से कहने में कामयाब रही और नल के नीचे से बुदबुदाते खून को साफ कर दिया। )
From linkbunnies.org (RSS) 17:00 The Reason Why And he manages to keep a straight face as he spouts this guff. ( linkbunnies.org (आरएसएस) से 17:00 कारण क्यों और वह एक सीधा चेहरा रखने का प्रबंधन करता है क्योंकि वह इस गफ को थपथपाता है। )

It was very difficult to keep a straight face.
How can you say that and keep a straight face?
I keep a straight face and the composure of a chemist dispensing a prescription.
I try and keep a straight face, but I can't help grinning at myself.
Barbara tried to keep a straight face, but in the end she just couldn't help laughing.
She looked so ridiculous it was hard to keep a straight face.
But sly winks are all they are- they never overwhelm the film and are never played with anything other than a straight face.
How can they tell that lie and keep a straight face?
I don't know how the others kept a straight face but I pulled out a handkerchief, pretending to blow my nose.