tell on

US /tel ɑːn/
UK /tel ɑːn/
"tell on" picture
1.

告发, 打小报告

to inform an authority figure about someone's bad behavior

:
If you don't stop, I'm going to tell on you.
如果你不停下来,我就要告发你。
The little boy decided not to tell on his sister.
小男孩决定不告发他的妹妹。