behind someone's back
彼らは陰で彼のことを笑う。
They laugh at him behind his back.
陰で悪く言うのはやめようよ。
Let's stop talking badly about people behind their backs.
陰で人の話をしてはいけないよ。
You shouldn't talk about people behind their backs.
人の陰で悪口を言うな。
Don't talk badly about people behind their backs.
陰で彼の悪口を言うな。
Don't talk badly about him behind his back.
人々は陰で彼を嘲笑したものだった。
People used to mock him behind his back.
陰で他人の悪口を言うべきでない。
You shouldn't badmouth others behind their backs.