This is no joking matter.; This is no joke.

这可不是闹着玩儿的事。

《新英汉大辞典》

There is no joking with him.

和他不能开玩笑。

youdao

There was no joking with him about it.

这件事和他开不得玩笑。

youdao

Are we saying that because it's a societal problem, no joking and no laughing are allowed?

CNN: Tracy Morgan and the limits of comedy

Friends might mean no harm in joking around, making inappropriate comments or tagging you in unsafe-for-office photos, but harm can be done when potential clients or employers see those jokes and tags.

FORBES: You Are the Company You Keep

No-one's smiling or joking around in training.

BBC: SPORT | Rugby Union | Internationals | Paul fired up for 'biggest test'