He could not make out why they were laughing at him.

他不明白他们为什么嘲笑他。

youdao

She couldn't resist laughing at him in those clothes.

看到他穿着那样的衣服，她忍不住笑了起来。

youdao

He had the awful feeling that everyone was laughing at him.

他有种极不舒服的感觉，觉得每个人都在笑话他。

youdao

And your little sister is pointing at him and laughing hysterically.

你的妹妹指着他哈哈大笑。

Don't 课堂 - SpeakingMax英语口语达人

But why are you so convinced that people are laughing at him and not...

NPR: 17 min 50 sec

And we're not laughing with him, we're laughing at him because we don't know him well enough to laugh with him.

NPR: 17 min 50 sec

"I was laughing at him, " Mr Barker said.

BBC: Brighton footballer 'exposed himself for photo'