I am not saying start being nasty.All I am advocating is to be nonchalant.

我不是说你应该开始变得让人讨厌，而是主张你要表现得若无其事。

youdao

I am not saying start being nasty. All I am advocating is to be nonchalant.

我不是说你应该开始变得让人讨厌，而是主张你要表现得若无其事。

youdao

'It'll be fine,' she replied, with a nonchalant shrug.

她若无其事地耸耸肩说：“会好的。”

《牛津词典》

Can gunfire be nonchalant?

BBC: The festive gunfire of Benghazi

The goal may be to look nonchalant, but to achieve that requires precision.

WSJ: Spring Fashion: Suited to the Occasion | Lanvin's Lucas Ossendrijver Picks | Off Duty Europe Spring 25