He feels they are laughing at him behind his back.

Always when I pass her she laughs behind my back.

They thought he didn't notice them laughing behind his back.

They were laughing at me behind their hands, so to speak.

She knew the figure was laughing at her behind his mask.

A man laughed from behind the mountain that was about to go in front of us.

Several students laughed behind her, as they understood what she was doing.

Sarah had the feeling he was laughing at her behind his serious eyes.

They laughed behind my back about something I would never show them.

She was quite sure his eyes had been laughing behind those dark lenses.