He feels they are laughing at him behind his back.

His men, he felt, laughed at him behind his back.

Always when I pass her she laughs behind my back.

Or maybe you'd have wondered if I'd been with another man and was laughing at you behind your back.

He was trying to lead and they were laughing at him behind his back.

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

They got the promotion, changed the uniform, hung out with their own kind and laughed at him behind his back.

Everyone in Rosington seemed to be laughing at him behind his back.

Or maybe they were all playing with him, laughing at him behind his back.

One of the Mac's men laughed discreetly behind his back.