Use 'a straight face' when you want to describe someone hiding their feelings, especially during humorous or silly moments.

Emotion Concealment

'A straight face' emphasizes neutrality amidst something typically funny or ridiculous.

Not Amused

Someone may use 'a straight face' to make a joke seem like a serious statement.

The phrase is used when it's important to hide laughter, such as in formal or inappropriate situations.

'A straight face' can indicate that someone is earnestly communicating something surprising or hard to believe.

Use 'a straight face' when describing a situation where serious composure is maintained despite potential disbelief or disagreement.